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What are threaded pipe fittings

What are threaded pipe fittings

Table of Contents

Threaded pipe fittings are used to connect piping system together. They consist of a threaded end and a corresponding end that can be either male or female. They come in various sizes from 1/8 inch to 6 inches, and they come in many different materials, including brass, stainless steel, and black malleable iron. There are several types of threaded pipe fittings available on the market today. Each one has its own benefits, so it is important to choose the right type for your application. Here we will discuss some of these types and their uses:

A threaded pipe fitting is a type of pipe fitting that is threaded on both the inside and outside. This allows it to be joined with a male threaded pipe, which has threads on its outside end.

The two most common types of threads are male threads (external) and female threads (internal). The external threading would be found on the outside end of a pipe fitting, while internal threading would be found on the inside end of another type of piping material such as stainless steel or copper tubing. These fittings can also come in different sizes depending upon how much pressure they can withstand before bursting apart due to over-pressure conditions within your home’s plumbing system where there are many different appliances connected together at once via their own individual pipes running through walls into basements/cellars etcetera.

Standards for Thread connections

Following Standards are used for designing threaded pipe fittings:

  • ASME B16.11: Forged Fittings, Socket Welding and Threaded.
  • MSS-SP-83: Class 3000 Steel Pipe Unions, Socket-Welding and Threaded.
  • ASME B16.3: Malleable Iron threaded pipe fittings.
  • ASME B16.4: Gray Iron threaded pipe fittings.
  • ASME B16.39: Malleable Iron Threaded Pipe Unions.
  • ASME B16.34: Valves — Flanged, Threaded, and Welding End.
  • ASME B16.39: Malleable Iron Threaded Pipe Unions, Class 150, 250, and 300.

Materials for threaded fittings

Threaded fittings can be manufactured from following materials:

Carbon Steel (A-105)

Chemical Properties

Grade C Mn Si P S Cr Mo Ni
A105 0.035 0.6 – 1.05 0.1 – 0.35 0.035 0.04 0.3 0.12 0.4
A350 LF2 0.3 0.6 – 1.35 0.15 – 0.3 0.035 0.04 0.3 0.12 0.4
A350 LF3 0.2 0.9 0.20-0.35 0.035 0.04 0.3 0.12 3.3 – 3.7
A694 F52 0.26-0.265 1.60-1.64  0.15-0.35 0.025-0.030  0.025-0.030 
A694 F56 0.26-0.265 1.60-1.64  0.15-0.35 0.025-0.030  0.025-0.030 
A694 F60 0.26-0.265 1.60-1.64  0.15-0.35 0.025-0.030  0.025-0.030 
A694 F65 0.26-0.265 1.60-1.64  0.15-0.35 0.025-0.030  0.025-0.030 
A694 F70 0.26-0.265 1.60-1.64  0.15-0.35 0.025-0.030  0.025-0.030 

Mechanical Properties

Grade Tensile Strength (Mpa) Yield Strength  (Mpa) Elongation (%)
A105 485 250 22
A350 LF2 485 – 655 250 22
A350 LF3 485 – 655 260 22
A694 F52 455 360 20
A694 F56 470 385 20
A694 F60 515 415 20
A694 F65 530 450 20
A694 F70 565 485 18

Alloy Steel (A-182)

Alloy Steel Chemical Composition

Chemical Composition Ranges and Limits, percent

AISI Number

C

Mn

P

Max.

S

Max.

Si

Ni

Cr

Mo

AISI 4130 0.28/0.33 0.40/0.60 0.035 0.040 0.20/0.35 0.80/1.10 0.15/0.25
AISI 4137 0.35/0.40 0.70/0.90 0.035 0.040 0.20/0.35 0.80/1.10 0.15/0.25
AISI 4140 0.38/0.43 0.75/1.00 0.035 0.040 0.20/0.35 0.80/1.10 0.15/0.25
AISI 4142 0.40/0.45 0.75/1.00 0.035 0.040 0.20/0.35 0.80/1.10 0.15/0.25
AISI 4145 0.43/0.48 0.75/1.00 0.035 0.040 0.20/0.35 0.80/1.10 0.15/0.25
AISI 4147 0.45/0.50 0.75/1.00 0.035 0.040 0.20/0.35 0.80/1.10 0.15/0.25
AISI 4150 0.48/0.53 0.75/1.00 0.035 0.040 0.20/0.35 0.80/1.10 0.15/0.25
AISI 4161 0.56/0.64 0.75/1.00 0.035 0.040 0.20/0.35 0.70/0.90 0.25/0.35
AISI 4320 0.17/0.22 0.45/0.65 0.035 0.040 0.20/0.35 1.65/2.00 0.40/0.60 0.20/0.30
AISI 4340 0.38/0.43 0.60/0.80 0.035 0.040 0.20/0.35 1.65/2.00 0.70/0.90 0.20/0.30
AISI 4419 0.18/0.23 0.45/0.65 0.035 0.040 0.20/0.35 0.45/0.60
AISI 4615 0.13/0.18 0.45/0.65 0.035 0.040 0.20/0.35 1.65/2.00 0.20/0.30
AISI 4620 0.17/0.22 0.45/0.65 0.035 0.040 0.20/0.35 1.65/2.00 0.20/0.30
AISI 4621 0.18/0.23 0.70/0.90 0.035 0.040 0.20/0.35 1.65/2.00 0.20/0.30
AISI 4626 0.24/0.29 0.45/0.65 0.035 0.040 0.20/0.35 0.70/1.00 0.15/0.25
AISI 4718 0.16/0.21 0.70/0.90 0.035 0.040 0.20/0.35 0.90/1.20 0.35/0.55 0.30/0.40
AISI 4720 0.17/0.22 0.50/0.70 0.035 0.040 0.20/0.35 0.90/1.20 0.35/0.55 0.15/0.25
AISI 4815 0.13/0.18 0.40/0.60 0.035 0.040 0.20/0.35 3.25/3.75 0.20/0.30
AISI 4817 0.15/0.20 0.40/0.60 0.035 0.040 0.20/0.35 3.25/3.75 0.20/0.30
AISI 4820 0.18/0.23 0.50/0.70 0.035 0.040 0.20/0.35 3.25/3.75 0.20/0.30
AISI 5120 0.17/0.22 0.70/0.90 0.035 0.040 0.20/0.35 0.70/0.90
AISI 5130 0.28/0.33 0.70/0.90 0.035 0.040 0.20/0.35 0.80/1.10
AISI 5132 0.30/0.35 0.60/0.80 0.035 0.040 0.20/0.35 0.75/1.00
AISI 5135 0.33/0.38 0.60/0.80 0.035 0.040 0.20/0.35 0.80/1.05
AISI 5140 0.38/0.43 0.70/0.90 0.035 0.040 0.20/0.35 0.70/0.90
AISI 5145 0.43/0.48 0.70/0.90 0.035 0.040 0.20/0.35 0.70/0.90
AISI 5147 0.46/0.51 0.70/0.95 0.035 0.040 0.20/0.35 0.85/1.15
AISI 5150 0.48/0.53 0.70/0.90 0.035 0.040 0.20/0.35 0.70/0.90
AISI 5155 0.51/0.59 0.70/0.90 0.035 0.040 0.20/0.35 0.70/0.90
AISI 6150 0.48/0.53 0.70/0.90 0.035 0.040 0.20/0.35 0.80/1.10 0.15 min.
AISI 8615 0.13/0.18 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8617 0.15/0.20 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8620 0.18/0.23 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8622 0.20/0.25 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8625 0.23/0.28 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8627 0.25/0.30 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8630 0.28/0.33 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8637 0.35/0.40 0.75/1.00 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8640 0.38/0.43 0.75/1.00 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8642 0.40/0.45 0.75/1.00 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8645 0.43/0.48 0.75/1.00 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8655 0.51/0.59 0.75/1.00 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.15/0.25
AISI 8720 0.18/0.23 0.70/0.90 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.20/0.30
AISI 8740 0.38/0.43 0.75/1.00 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.20/0.30
AISI 8822 0.20/0.25 0.75/1.00 0.035 0.040 0.20/0.35 0.40/0.70 0.40/0.60 0.30/0.40
AISI 9254 0.51/0.59 0.60/0.80 0.035 0.040 1.20/1.60 0.60/0.80
AISI 9255 0.51/0.59 0.70/0.95 0.035 0.040 1.80/2.20
AISI 9260 0.56/0.64 0.75/1.00 0.035 0.040 1.80/2.20

Grades shown in the above list with prefix letter E are normally made only by the basic electric furnace process. All others are normally manufactured by the basic open hearth or basic oxygen processes but may be manufactured by the basic electric furnace process with adjustments in phosphorus and sulphur.

Stainless Steel (A-182)

The elemental chemical composition of stainless steel is mainly composed of iron (FE) and chromium (CR). The chemical composition of other alloy elements also includes carbon (c), silicon (SI), manganese (MN), phosphorus (P), sulfur (s), nickel (Ni), molybdenum (MO), titanium (TI), nitrogen (n) and copper (Cu). Steel is corrosion resistant only when the percentage composition of chromium reaches a certain value. Therefore, the chromium content of stainless steel metal is generally at least 10.5%.
The following table lists the chemical composition of stainless steel alloys, including austenite SS 304, 304L 316, 316L, 321, 303, 302, 301, 904L, 201, martensite SS 440A, 440b, 440C, 420, ferrite SS 430, duplex stainless steel 2205, 2507, 329, etc.
Note: UOS (unless otherwise specified)

Stainless Steel Chemical Composition Chart, Percentage (%)
Stainless Steel C, ≤ Mn, ≤ P, ≤ S, ≤ Si, ≤ Cr Ni Mo N, ≤ Other Elements, ≤, UOS
304 0.08 2.00 0.045 0.03 1.00 18.0-20.0 8.0-11.0
304L 0.03 2.00 0.045 0.03 1.00 18.0-20.0 8.0-12.0
316 0.08 2.00 0.045 0.030 1.00 16.0-18.0 10.0-14.0 2.00-3.00
316L 0.03 2.00 0.045 0.030 1.00 16.0-18.0 10.0-14.0 2.00-3.00
321 0.08 2.00 0.045 0.03 1.00 17.0-19.0 9.0-12.0 0.10 ≥ Ti 5×(C+N), ≤ 0.70
201 0.15 5.50-7.50 0.06 0.03 1.00 16.0-18.0 3.5-5.5 0.25
202 0.15 7.50-10.00 0.06 0.03 1.00 17.0-19.0 4.0-6.0 0.25
205 0.12-0.25 14.0-15.5 0.06 0.03 1.00 16.5-18.0 1.0-1.7 0.32-0.40
301 0.15 2.00 0.045 0.03 1.00 16.0-18.0 6.0-8.0 0.10
301L 0.03 2.00 0.045 0.03 1.00 16.0-18.0 6.0-8.0 0.20
301LN 0.03 2.00 0.045 0.03 1.00 16.0-18.0 6.0-8.0 0.07-0.20
302 0.15 2.00 0.045 0.03 0.75 17.0-19.0 8.0-10.0 0.10
302B 0.15 2.00 0.045 0.03 2.00-3.00 17.0-19.0 8.0-10.0 0.10
303 0.15 2.00 0.2 ≥0.15 1.00 17.0-19.0 8.0-10.0
303Se 0.15 2.00 0.2 0.06 1.00 17.0-19.0 8.0-10.0 Se 0.15
304H 0.04-0.10 2.00 0.045 0.03 0.75 18.0-20.0 8.0-10.5
304N 0.08 2.00 0.045 0.03 1.00 18.0-20.0 8.0-11.0 0.10-0.16
304LN 0.03 2.00 0.045 0.03 1.00 18.0-20.0 8.0-11.0 0.10-0.16
305 0.12 2.00 0.045 0.03 1.00 17.0-19.0 11.0-13.0
308 0.08 2.00 0.045 0.03 1.00 19.0-21.0 10.0-12.0
309 0.2 2.00 0.045 0.03 1.00 22.0-24.0 12.0-15.0
309S 0.08 2.00 0.045 0.03 1.00 22.0-24.0 12.0-15.0
309H 0.04-0.10 2.00 0.045 0.03 0.75 22.0-24.0 12.0-15.0
309Cb 0.08 2.00 0.045 0.03 1.00 22.0-24.0 12.0-16.0 ≥ Cb 10 x C, ≤1.10
309HCb 0.04-0.10 2.00 0.045 0.03 0.75 22.0-24.0 12.0-16.0 ≥ Cb 10 x C, ≤1.10
310 0.25 2.00 0.045 0.03 1.5 24.0-26.0 19.0-22.0
310S 0.08 2.00 0.045 0.03 1.5 24.0-26.0 19.0-22.0
310H 0.04-0.10 2.00 0.045 0.03 0.75 24.0-26.0 19.0-22.0
310Cb 0.08 2.00 0.045 0.03 1.5 24.0-26.0 19.0-22.0 ≥ Cb 10 x C, ≤ 1.10
310 MoLN 0.02 2.00 0.03 0.01 0.5 24.0-26.0 20.5-23.5 1.60-2.60 0.09-0.15
314 0.25 2.00 0.045 0.03 1.50-3.00 23.0-26.0 19.0-22.0
316H 0.04-0.10 2.00 0.045 0.03 0.75 16.0-18.0 10.0-14.0 2.00-3.00
316Ti 0.08 2.00 0.045 0.03 1.00 16.0-18.0 10.0-14.0 2.00-3.00 0.1 ≥ Ti 5 × (C + N), ≤0.70
316Cb 0.08 2.00 0.045 0.03 1.00 16.0-18.0 10.0-14.0 2.00-3.00 0.1 ≥ Cb 10 × C, ≤ 1.10
316N 0.08 2.00 0.045 0.03 1.00 16.0-18.0 10.0-14.0 2.00-3.00 0.10-0.16
316LN 0.03 2.00 0.045 0.03 1.00 16.0-18.0 10.0-13.0 2.00-3.00 0.10-0.16
317 0.08 2.00 0.045 0.03 1.00 18.0-20.0 11.0-15.0 3.0-4.0 0.1
317L 0.03 2.00 0.045 0.03 0.75 18.0-20.0 11.0-15.0 3.0-4.0 0.1
317LM 0.03 2.00 0.045 0.03 0.75 18.0-20.0 13.5-17.5 4.0-5.0 0.2
317LMN 0.03 2.00 0.045 0.03 0.75 17.0-20.0 13.5-17.5 4.0-5.0 0.10-0.20
317LN 0.03 2.00 0.045 0.03 0.75 18.0-20.0 11.0-15.0 3.0-4.0 0.10-0.22
321 0.08 2.00 0.045 0.03 1.00 17.0-19.0 9.0-12.0 0.1 ≥ Ti 5 × (C + N), ≤ 0.70
321H 0.04-0.10 2.00 0.045 0.03 0.75 17.0-19.0 9.0-12.0 ≥ Ti 4 × (C + N), ≤ 0.70
334 0.08 1.00 0.03 0.015 1.00 18.0-20.0 19.0-21.0 Al 0.15-0.60, Ti 0.15-0.60
347 0.08 2.00 0.045 0.03 1.00 17.0-19.0 9.0-12.0 ≥ Cb 10 × C, ≤ 1.00
347H 0.04-0.10 2.00 0.045 0.03 0.75 17.0-19.0 9.0-13.0 ≥ Cb 8 × C, ≤ 1.00
347LN 0.005-0.020 2.00 0.045 0.03 1.00 17.0-19.0 9.0-13.0 0.06-0.10 Cb 0.20-0.50, 15 × C ≥
348 0.08 2.00 0.045 0.03 1.00 17.0-19.0 9.0-12.0 Cb 10×C-1.10, Ta 0.10, Co 0.20
348H 0.04-0.10 2.00 0.045 0.03 0.75 17.0-19.0 9.0-13.0 (Cb + Ta) 8×C ≥ , 1.00 ≤, Ta 0.10, Co 0.20
2205 0.03 2.00 0.03 0.02 1.00 22.0-23.0 4.5-6.5 3.0-3.5 0.14-0.20
2304 0.03 2.5 0.04 0.03 1.00 21.5-24.5 3.0-5.5 0.05-0.60 0.05-0.60
255 0.04 1.5 0.04 0.03 1.00 24.0-27.0 4.5-6.5 2.9-3.9 0.10-0.25 Cu 1.50-2.50
2507 0.03 1.2 0.035 0.02 0.8 24.0-26.0 6.0-8.0 3.0-5.0 0.24-0.32 Cu ≤0.50
329 0.08 1.00 0.04 0.03 0.75 23.0-28.0 2.0-5.00 1.00-2.00
403 0.15 1.00 0.04 0.03 0.5 11.5-13.0
405 0.08 1.00 0.04 0.03 1.00 11.5-14.5 0.5 Al 0.10-0.30
410 0.08-0.15 1.00 0.04 0.03 1.00 11.5-13.5
410S 0.08 1.00 0.04 0.03 1.00 11.5-13.5 0.6
414 0.15 1.00 0.04 0.03 1.00 11.5-13.5 1.25-2.50
416 0.15 1.25 0.06 ≥0.15 1.00 12.0-14.0
416Se 0.15 1.25 0.06 ≥0.06 1.00 12.0-14.0 Se 0.15
420 0.15, ≥ 1.00 0.04 0.03 1.00 12.0-14.0
420F 0.30-0.40 1.25 0.06 ≥0.15 1.00 12.0-14.0 0.5 Cu 0.60
420FSe 0.20-0.40 1.25 0.06 0.15 1.00 12.0-14.0 0.5 Se 0.15; Cu 0.60
422 0.20-0.25 0.50-1.00 0.025 0.025 0.5 11.0-12.5 0.50-1.00 0.90-1.25 V (0.20-0.30), W (0.90-1.25)
429 0.12 1.00 0.04 0.03 1.00 14.0-16.0
430 0.12 1.00 0.04 0.03 1.00 16.0-18.0
430F 0.12 1.25 0.06 ≥0.15 1.00 16.0-18.0
430FSe 0.12 1.25 0.06 0.06 1.00 16.0-18.0 Se 0.15
439 0.03 1.00 0.04 0.03 1.00 17.0-19.0 0.5 0.03 ≥ Ti [0.20+4(C+N)], ≤ 1.10; Al 0.15
431 0.2 1.00 0.04 0.03 1.00 15.0-17.0 1.25-2.50
434 0.12 1.00 0.04 0.03 1.00 16.0-18.0 0.75-1.25
436 0.12 1.00 0.04 0.03 1.00 16.0-18.0 0.75-1.25 ≥ Cb 5×C, ≤ 0.80
440A 0.60-0.75 1.00 0.04 0.03 1.00 16.0-18.0 ≤0.75
440B 0.75-0.95 1.00 0.04 0.03 1.00 16.0-18.0 ≤0.75
440C 0.95-1.20 1.00 0.04 0.03 1.00 16.0-18.0 ≤0.75
440F 0.95-1.20 1.25 0.06 0.15 1.00 16.0-18.0 0.5 Cu ≤0.60
440FSe 0.95-1.20 1.25 0.06 0.06 1.00 16.0-18.0 0.5 Se ≤0.15; Cu ≤0.60
442 0.2 1.00 0.04 0.04 1.00 18.0-23.0 0.6
444 0.025 1.00 0.04 0.03 1.00 17.5-19.5 1.00 1.75-2.50 0.035 Ti+Cb 0.20+4 × (C+N)-0.80
446 0.2 1.5 0.04 0.03 1.00 23.0-27.0 0.75 0.25
800 0.1 1.5 0.045 0.015 1.00 19.0-23.0 30.0-35.0 Cu 0.75; ≥ FeH 39.5; Al 0.15-0.60
800H 0.05-0.10 1.5 0.045 0.015 1.00 19.0-23.0 30.0-35.0 Cu 0.75; ≥ FeH 39.5; Al 0.15-0.60
904L 0.02 2.00 0.045 0.035 1.00 19.0-23.0 23.0-28.0 4.00-5.00 0.1 Cu 1.00-2.00
Alloy 20 0.07 2.00 0.045 0.035 1.00 19.0-21.0 32.0-38.0 2.00-3.00 Cu 3.0-4.0; ≥ Nb 8 × C; ≤1.00
XM-1 0.08 5.0-6.5 0.04 0.18-0.35 1.00 16.00-18.0 5.0-6.5 Cu 1.75-2.25
XM-2 0.15 2.00 0.05 0.11-0.16 1.00 17.0-19.0 8.0-10.0 0.40-0.60 Al 0.60-1.00
XM-5 0.15 2.5-4.5 0.2 ≥0.25 1.00 17.0-19.0 7.0-10.0
XM-6 0.15 1.50-2.50 0.06 ≥0.15 1.00 12.0-14.0
XM-10 0.08 8.0-10.0 0.045 0.03 1.00 19.0-21.5 5.5-7.5 0.15-0.40
XM-11 0.04 8.0-10.0 0.045 0.03 1.00 19.0-21.5 5.5-7.5 0.15-0.40
XM-15 0.08 2.00 0.03 0.03 1.50-2.50 17.0-19.0 17.5-18.5
XM-17 0.08 7.50-9.00 0.045 0.03 0.75 17.5-22.0 5.0-7.0 2.00-3.00 0.25-0.50
XM-18 0.03 7.50-9.00 0.045 0.03 0.75 17.5-22.0 5.0-7.0 2.00-3.00 0.25-0.50
XM-19 0.06 4.0-6.0 0.045 0.03 1.00 20.5-23.5 11.5-13.5 1.50-3.00 0.20-0.40 Cb 0.10-0.30, V 0.10-0.30
XM-21 0.08 2.00 0.045 0.03 0.75 18.0-20.0 8.0-10.5 0.16-0.30
XM-27 0.01 0.4 0.02 0.02 0.4 25.0-27.5 0.5 0.75-1.50 0.015 Cu 0.20; Cb 0.05-0.20; (Ni + Cu) 0.50
XM-33 0.06 0.75 0.04 0.02 0.75 25.0-27.0 0.5 0.75-1.50 0.04 Cu 0.20; Ti 0.20-1.00; ≥ Ti 7(C+N)
XM-34 0.08 2.5 0.04 ≥0.15 1.00 17.5-19.5 1.50-2.50
PH 13-8Mo 0.05 0.2 0.01 0.008 0.1 12.25-13.25 7.5-8.5
15-5 PH 0.07 1 0.04 0.03 1 14.0-15.5 3.5-5.5 2.5-4.5 Cu; 0.15-0.45 Nb
17-4 PH 0.07 1 0.04 0.03 1 15.5-17.5 3.0-5.0 3.0-5.0 Cu; 0.15-0.45 Nb
17-7 PH 0.09 1 0.04 0.04 1 16.0-18.0 6.5-7.75 0.75-1.5 Al
Stainless Steel C, ≤ Mn, ≤ P, ≤ S, ≤ Si, ≤ Cr Ni Mo N, ≤ Other Elements, ≤, UOS

Low Alloy Steel (A-350)

Chemical Composition of Low Alloy Steel (A-350)

Chemical Composition of ASTM A182 Low Alloy Steels, %
ID. Symbol* C Mn P S Si Cr Mo Others
F1 0.28 0.60-0.90 0.045 0.045 0.15-0.35 0.44-0.65
F2 0.05-0.21 0.60-0.80 0.040 0.040 0.10-0.60 0.50-0.81 0.44-0.65
F5 0.15 0.30-0.60 0.030 0.030 0.50 4.0-6.0 0.44-0.65 *A
F5A 0.25 0.60 0.040 0.030 0.50 4.0-6.0 0.44-0.65 *B
F9 0.15 0.30-0.60 0.030 0.030 0.50-1.00 8.0-10.0 0.90-1.10
F10 0.10-0.12 0.50-0.80 0.040 0.030 1.00-1.40 7.0-9.0 *C
F91 0.08-0.12 0.30-0.60 0.020 0.010 0.20-0.50 8.0-9.5 0.85-1.05 *D
F92 0.07-0.13 0.30-0.60 0.020 0.010 0.50 8.5-9.5 0.30-0.60 *E
F122 0.07-0.14 0.70 0.020 0.010 0.50 10.00-11.50 0.25-0.60 *F
F911 0.09-0.13 0.30-0.60 0.020 0.010 0.10-0.50 8.5-9.5 0.90-1.10 *G
F11 CLASS1 0.05-0.15 0.30-0.60 0.030 0.030 0.50-1.00 1.00-1.50 0.44-0.65
F11 CLASS2 0.10-0.20 0.30-0.80 0.040 0.040 0.50-1.00 1.00-1.50 0.44-0.65
F11 CLASS3 0.10-0.20 0.30-0.80 0.040 0.040 0.50-1.00 1.00-1.50 0.44-0.65
F12 CLASS1 0.05-0.15 0.30-0.60 0.045 0.045 0.50 0.80-1.25 0.44-0.65
F12 CLASS2 0.10-0.20 0.30-0.80 0.040 0.040 0.10-0.60 0.80-1.25 0.44-0.65
F21 0.05-0.15 0.30-0.60 0.040 0.040 0.50 2.7-3.3 0.80-1.06
F3V 0.05-0.10 0.30-0.60 0.020 0.020 0.10 2.8-3.2 0.90-1.10 *H
F3VCb 0.10-0.15 0.30-0.60 0.020 0.010 0.10 2.7-3.3 0.90-1.10 *I
F22 CLASS1 0.05-0.15 0.30-0.60 0.040 0.040 0.50 2.00-2.50 0.87-1.13
F22 CLASS3 0.05-0.15 0.30-0.60 0.040 0.040 0.50 2.00-2.50 0.87-1.13
F22V 0.11-0.15 0.30-0.60 0.015 0.010 0.10 2.00-2.50 0.90-1.10 *J
F23 0.04-0.10 0.10-0.60 0.030 0.010 0.50 1.90-2.60 0.05-0.30 *K
F24 0.05-0.10 0.30-0.70 0.020 0.010 0.15-0.45 2.20-2.60 0.90-1.10 *L
FR 0.20 0.40-1.06 0.045 0.050 *M
F36 0.10-0.17 0.80-1.20 0.030 0.025 0.25-0.50 0.30 0.25-0.50 *N

*”ID.S” refers to the identification symbol of the grades stipulated by ASTM A182.
*All values are maximum unless a range is provided or otherwise specified.
*A – Ni:≤0.50; *B – Ni:≤0.50; *C – Ni:19-22;
*D – Ni:≤0.40,Co:0.06-0.10%,N:0.03-0.07,Al:≤0.02,V:0.18-0.25,T≤0.01%,Zr≤0.01.
*E – Ni:≤0.40,Co:0.04-0.09;V:0.15-0.25,N:0.030-0.070,Al:≤0.02,W:1.50-2.00,B:0.001-0.006,Ti&Zr:≤0.01.
*F – Ni:≤0.50,Co:0.04-0.10,V:0.15-0.30,B:≤0.005,N:0.04-0.10,Al:≤0.02,Cu:0.30-1.70,W:1.5-2.5,Ti&Zr:≤0.01.
*G – Ni:≤0.40,Co:0.06-0.10,W:0.90-1.10,Al:≤0.02,N:0.04-0.09,V:0.18-0.25,B:0.0003-0.006,Ti&Zr:≤0.01.
*H – Ti:0.015-0.035,V:0.20-0.30,B:0.001-0.003.
*I – Ni:≤0.25,Co:0.015-0.070,Ti:≤0.015,V:0.20-0.30,Cu:≤0.25,Ca:0.0005-0.0150.
*J – Ni:≤0.25,Co:≤0.07,Ti≤0.030,Cu≤0.20,V:0.25-0.35,B:≤0.002,Ca:≤0.015.
*K – Ni:≤0.40,Co:0.02-0.08,Ti:0.005-0.060,V:0.20-0.30,B:0.001-0.006,N:≤0.015,Al:≤0.030,W:1.45-1.75.
*L – Ti:0.06-0.10,V:0.20-0.30,N:≤0.12,Al:≤0.020,B:0.0015-0.0070
*M – Ni:1.60-2.24,Cu:0.75-1.25. *N – Ni:1.00-1.30,Co:0.015-0.045,N:≤0.20,Al:≤0.050,Cu:0.50-0.80,V:≤0.02.
*All chemical content values listed above from *A to *N shall be furnished with the unit of %.

Mechanical Properties of Low Alloy Steel (A-350)

Mechanical Properties of ASTM A182 Low Alloy Steels
Grade Tensile Strength
min. ksi[MPa]
Yield Strength
min. ksi[MPa]
Elongation, min. % Reduction of
Area, min. %
Brinell Hardness
Number, HBW
F1 70[485] 40[275] 20 30 143-192
F2 70[485] 40[275] 20 30 143-192
F5 70[485] 40[275] 20 35 143-217
F5a 90[620] 65[450] 22 50 187-248
F9 85[585] 55[380] 20 40 179-217
F10 80[550] 30[205] 30 50
F91 90[620] 60[415] 20 40 190-248
F92 90[620] 64[440] 20 45 ≤269
F122 90[620] 58[400] 20 40 ≤250
F911 90[620] 64[440] 18 40 187-248
F11 Class 1 60[415] 30[205] 20 45 121-174
F11 Class 2 70[485] 40[275] 20 30 143-207
F11 Class 3 75[515] 45[310] 20 30 156-207
F12 Class 1 60[415] 32[220] 20 45 121-174
F12 Class 2 70[485] 40[275] 20 30 143-207
F21 75[515] 45[310] 20 30 156-207
F3V & F3VCb 85-110[585-760] 60[415] 18 45 174-237
F22 Class 1 60[415] 30[205] 20 35 ≤170
F22 Class 3 75[515] 45[310] 20 30 156-207
F22V 85-110[585-780] 60[415] 18 45 174-237
F23 74[510] 58[400] 20 40 ≤220
F24 85[585] 60[415] 20 40 ≤248
FR 63[435] 46[315] 25 38 ≤197
F36 Class 1 90[620] 64[440] 15 ≤252
F36 Class 2 95.5[660] 66.5[460] 15 ≤252

Heat Treatment of Low Alloy Steel (A-350)

Heat Treatment of ASTM A182 Alloy Steels
Grade Heat Treatment Process
F1 Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1650°F[900°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1150°F[620°C].
F2 Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1650°F[900°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1150°F[620°C].
F5, F5a Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1750°F[955°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1250°F[675°C].
F9 Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1750°F[955°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1250°F[675°C].
F10 Type: solution treat and quench; Minimum solutioning temperature:1900°F[1040°C]; Cooling media: liquid; Quenching cool below: 500°F[260°C]
F91 Type: normalize and temper; Temperature range of austenitizing/solutioning:1900-1975°F[1040-1080°C]; air cool; Temperature range of tempering: 1350-1470°F[730-800°C].
F92 Type: normalize and temper; Temperature range of austenitizing/solutioning:1900-1975°F[1040-1080°C]; air cool; Temperature range of tempering: 1350-1470°F[730-800°C].
F122 Type: normalize and temper; Temperature range of austenitizing/solutioning:1900-1975°F[1040-1080°C]; air cool; Temperature range of tempering: 1350-1470°F[730-800°C].
F911 Type: normalize and temper; Temperature range of austenitizing/solutioning:1900-1975°F[1040-1080°C]; air or liquid cool; Temperature range of tempering: 1365-1435°F[740-780°C].
F11 Class 1, 2, 3 Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1650°F[900°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1150°F[620°C].
F12 Class 1, 2 Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1650°F[900°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1150°F[620°C].
F21, F3V, F3VCb Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1750°F[955°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1250°F[675°C].
F22, Class 1, 3 Type: anneal, or normalize and temper; Minimum austenitizing/solutioning temperature:1650°F[900°C]; Cooling media:furnace or air cool; Minimum tempering temperature:1250°F[675°C].
F22V Type: normalize and temper, or quench and temper; Minimum austenitizing/solutioning temperature: 1650°F[900°F]; air or liquid cool; Minimum tempering temperature: 1250°F[675°C].
F23 Type: normalize and temper; Temperature range of austenitizing/solutioning:1900-1975°F[1040-1080°C]; air cool; Temperature range of tempering: 1350-1470°F[730-800°C].
F24 Type: normalize and temper; Temperature range of austenitizing/solutioning:1800-1975°F[980-1080°C]; air or liquid cool; Temperature range of tempering: 1350-1470°F[730-800°C].
FR Type: anneal, or normalize, or normalize and temper; Minimum austenitizing/solutioning temperature: 1750°F[955°C]; air or furnace cool; Minimum tempering temperature: 1250°F[675°C].
F36 Class 1 Type: normalize and temper; Minimum austenitizing/solutioning temperature:1650°F[900°C]; Cooling media:air cool; Minimum tempering temperature:1100°F[595°C].
F36 Class 2 Type: normalize and temper, or quench and temper; Minimum austenitizing/solutioning temperature:1650°F[900°C]; Cooling media:air cool or liquid; Minimum tempering temperature:1100°F[595°C].

*After hot working, the ASTM A182 low alloy steel forings shall be cooled to a temperature below 1000°F[538°C] prior to heat treatment.

Typical Steel Grades, UNS designation, and Steel Names of Low Alloy Steel (A-350)

Steel Grades UNS Designation Steel Names
ASTM A182 F1 K12822 C-0.5Mo
ASTM A182 F2 K12122 0.5Cr-0.5Mo
ASTM A182 F5 K41545 5Cr-0.5Mo
ASTM A182 F5a K42544 5Cr-0.5Mo
ASTM A182 F9 K90941 9Cr-1Mo
ASTM A182 F10 S33100 20Ni-8Cr
ASTM A182 F91 K90901 9Cr-1Mo-V
ASTM A182 F92 K92460 9Cr-0.5Mo-1.8W-V
ASTM A182 F11 CL1 K11597 1.25Cr–0.5Mo–Si
ASTM A182 F11 CL2 K11572 1.25Cr–0.25Mo–Si
ASTM A182 F11 CL3 K11572 1.25Cr–0.5Mo–Si
ASTM A182 F12 CL1 K11562 1Cr-0.5Mo
ASTM A182 F12 CL2 K11564 1Cr-0.5Mo
ASTM A182 F22 CL1 K21590 2.25Cr-1Mo
ASTM A182 F22 CL3 K21590 2.25Cr-1Mo
ASTM A182 F21 K31545 3Cr-1Mo
ASTM A182 F122 K91271
ASTM A182 F911 K91061
ASTM A182 F3V K31830
ASTM A182 F3VCb K31390
ASTM A182 F22V K31835 2.25Cr-1Mo-V
ASTM A182 F23 K41650
ASTM A182 F24 K30736 2.25Cr-1Mo-0.25V-Ti-B
ASTM A182 FR K22035
ASTM A182 F36 K21001 1.15Ni-0.65Cu-Mo-Co

Duplex Stainless Steel

Duplex Stainless Steel Chemical Composition

Type

Example grades

Composition

PREN

Cr%

Ni%

Mo%

N%

Lean

S31500, S32304, S32404

20-24

1-5

0.1-0.3

0.1-0.22

24-25

Standard

S31803, S32205

21-23

4.5-6

2.5-3.5

0.1-0.22

33-35

Super-duplex

S32520, S32550, S32750

24-29

4.5-8

2.7-4.5

0.1-0.35

>40

Hyper-duplex

S32707, S33207

27

6.5

5

0.4

49

Cooper Nickel

The most common copper-nickel alloys being 90/10 cupronickel and 70/30 cupronickel, the chemical composition of both are given below.

90/10 Cupronickel

Copper 86 – 89.7%
Nickel 9.0 – 11.0%
Iron 1.0 – 2.0%
Manganese 0.3 – 1.0%

70/30 Cupronickel

Copper 70.1 – 65.5%
Nickel 29.0 – 32.0%
Iron 0.5 – 1.5%
Manganese 0.4 – 1.0%

How do i identify threaded fitting thread types?

Types of common pipe threads

  • NPT or NPs (tapered or straight for national piping). Most common in North America.
  • MIP or FIP (male or female iron pipe). Same thread size as NPT.
  • BSP (T) or BSP (s) (British standard pipe cone or straight pipe). Most common in Europe.
  • Compression. A unique thread joint that does not match other thread types.
  • UNS (national unified and dedicated). Some are compatible with compression joints.

BSP – British Standard Pipe

The BSP, or Whitworth thread, is a family of thread standards that has been adopted internationally, except in the United States. This thread form is based on a 55° V-thread with rounded roots and crests, as seen in Figure 2. For a thread that conforms to BSP, the major diameter of the pipe thread is slightly smaller than the actual OD of the pipe, and the minor diameter will be very close to (smaller than) the inside diameter of the female thread. There are two types of BSP threads:

  1. BSPP: Both the male and female threads are parallel. BSPP connections are widely used in UK, Europe, Asia, Australia, New Zealand and South Africa. Sizes can be seen in Table 1.
  2. BSPT: The male threads are tapered and the female threads are commonly parallel. BSPT connections are especially popular in China and Japan. Sizes can be seen in Table 2.

BSPP vs BSPT

BSPP thread is also British standard. It is a parallel thread fitting that uses a bonded seal ring to do the sealing. For historical reasons, BSPP has other different names at the same time. Such as BSPF ( British standard pipe fitting), BSPM(British Standard Pipe Mechanical) and PS (British Standard Pipe Straight) and so on.
BSPT thread is similar to NPT except for one important difference. The angle across the flanks of threads is 55 degrees instead of 60 degree as it is for NPT thread. Thus an NPT male thread could fit into BSPT female thread, but couldn’t sealing. That may make it dangerous while using.

bsp thread - What are threaded pipe fittings

A BSPP male parallel thread profile (left) and a BSPT taperd male thread profile (right)

BSP threads are identified with letters each of which represents the type of thread and their associated standards1:

  • G: external and internal parallel (ISO 228, DIN 259) – BSPP
  • R: external taper (ISO 7, EN 10226, BS 21, JIS B 0203) – BSPT
  • Rp: Internal parallel (ISO 7-1, EN 10226) – BSPT
  • Rc: internal taper (ISO 7) – BSPT
  • Rs: external parallel (BS 21) – BSPT- Obsolete

1ISO 7: Pipe threads where pressure-tight joints are made on the threads. ISO 228: Pipe threads where pressure-tight joints are not made on the threads.

Labeling Example: EN 10226 Rp 2 ½
This refers to a British Standard Pipe thread tapered (EN 10226) with an internal parallel form (Rp) and a nominal size of 2 ½.

The actual sizes of the most commonly used BSP threads are listed in Table 1 and Table 2 for BSPP and BSPT threads respectively. Table 3 provides data on pipe sizes associated with these threads.

Note: Each thread size is identified with a number which has little to do with the actual size of the thread. This discrepancy originates from amendments in industrial practices and standardisation throughout the history of standardisation of pipe threads. Therefore, always compare measurements with actual sizes listed in the tables.

Table 1: BSPP (G) – British Standard Pipe Parallel
Nominal Thread Size Major Diameter (mm) Minor Diameter (mm) TPI (in-1)
G 1/16 7.723 6.561 28
G 1/8 9.728 8.566 28
G 1/4 13.157 11.445 19
G 3/8 16.662 14.950 19
G 1/2 20.955 18.631 14
G 3/4 26.441 24.117 14
G 1 33.249 30.291 11
G 2 59.614 56.656 11
Table 2: BSPT (R/Rp) – British Standard Pipe Tapered
Nominal Male Tapered Thread Size (inch) Nominal Female Parallel Thread Size (inch) Major Diameter (mm) Minor Female Diameter (mm) TPI (in-1)
R 1/16 RP 1/16 7.723 6.490 28
R 1/8 RP 1/8 9.728 8.495 28
R 1/4 Rp 1/4 13.157 11.341 19
R 3/8 Rp 3/8 16.662 14.846 19
R 1/2 Rp 1/2 20.955 18.489 14
R 3/4 Rp 3/4 26.441 23.975 14
R 1 Rp 1 33.249 30.111 11
R 2 Rp 2 59.614 56.476 11
Table 3: British Standard Pipe Dimensions for Standard Thread Sizes
Nominal G / R size (in) Corresponding Pipe
DN (mm) Actual OD (mm) Wall (mm)
1/16 3    
1/8 6 10.2 2
1/4 8 13.5 2.3
3/8 10 17.2 2.3
1/2 15 21.3 2.6
3/4 20 26.9 2.6
1 25 33.7 3.2
2 50 60.3 3.6

npt thread - What are threaded pipe fittings

NPT thread profile mating with the top being a fitting internal thread and the bottom being a pipe external thread.

NP – National (American) Pipe Thread

The American national pipe thread was created based on a 60° V-thread with flattened peaks and valleys (Figure 3) and is widely used in the US and Canada. There are two types of NP threads:

  1. NPS: Straight threads, meaning the male and female threads are parallel.
  2. NPT: Tapered threads, meaning the male and female threads are tapered. NPT threads are more commonly used. NPT Thread specifications are based on ANSI B1.20.1 and the threads sizes can be seen in Table 4.
Table 4: NPT – National (American) Pipe Thread Tapered
Nominal Thread Size (inch) Major Diameter (mm) TPI (in-1)
1/16 7.950 27
1/8 10.287 27
1/4 13.716 18
3/8 17.145 18
1/2 21.336 14
3/4 26.670 14
1 33.401 11.5
2 60.325 11.5

Labeling Example: 3/8 – 18 NPT

National pipe threads are designated with their nominal size (3/8) followed by number of threads per inch (18) and the symbol for the thread series (NPT).

Note: NPS (National Pipe Straight) is not to be confused with NPS (Nominal Pipe Size) which is an American set of standards for pipes. For a given outside diameter, NPS (Nominal Pipe Size) provides multiple pipe schedules (wall thicknesses) while the pipe thread profile remains the same among them.

M – Metric Thread (ISO)

metric threads - What are threaded pipe fittings

Metric Thread profile

The Metric Thread is one of the first internationally agreed general-purpose thread type. The V-shaped thread form has a 60° flank angle and male and female threads are both parallel (Figure 4). Metric Threads come in different pitch sizes for a given diameter: coarse pitch and fine pitches. Coarse threads have the default pitch size whereas fine threads have smaller pitch sizes and are used less often. As a result, coarse threads are identified by diameter only while fine threads are recognized by diameter as well as pitch size.

Metric threads come in two different pitch sizes for a given diameter:

  1. Coarse Pitch: These have the default pitch size according to Table 5 and are the most commonly used. They adhere to ISO 724 (DIN 13-1).
  2. Fine Pitch: These have a smaller pitch size and in the labeling they require the diameter of the pitch size. They adhere to ISO 724 (DIN 13-2 to 11).

Labeling Example: M8
This refers to a metric coarse thread with a diameter of 8 mm (which with reference Table 5, corresponds to a pitch size of 1 mm)

Labeling Example: M4 x 0.5
This indicates a fine thread with a diameter of 4 mm and a pitch size of 0.5 mm.

M 10M 10

Table 5: Metric Threads (Coarse)
Thread Size (mm) Major Diameter (mm) Minor Diameter (mm) Pitch (mm)
M 3 2.98 2.459 0.5
M 4 3.978 3.242 0.7
M 5 4.976 4.134 0.8
M 6 5.976 4.917 1
M 8 7.974 6.917 1.25
M 10 9.968 8.376 1.5
M 12 11.97 10.106 1.75
M 16 15.96 13.835 2
M 20 19.96 17.294 2.5
M 24 23.95 20.752 3

You can force the threads together, but if they do not match exactly, your joint will not seal. Most pipe thread types are not interchangeable. NPT, MIP and FIP can be used together, but cannot be matched with any other type of thread. One NPT is not suitable for one BSP. Many times, the connector itself will tell you what thread type you need. These letters may be engraved or printed on them.

How Many Types of Threaded Pipe Fittings

Threaded fittings can be subdivided into more than a dozen types, covering a variety of forms from straight to bent connections, including flat-headed external threads (short joints), which are a common fitting for pipe connections; threaded crosses, which are used to connect four pipes together; threaded tees, which are used to connect three pipes together; and single-headed threaded short joints: double-headed threaded short joints, hexagonal plugs, square plugs, threaded caps, threaded elbows In addition, there are hexagonal head internal and external threaded joints (core filler), hexagonal double threaded joints of the same diameter, single head threaded pipe clamps, hexagonal double threaded joints of different diameter, threaded couplings, double head threaded pipe caps, socket couplings, round head pipe plugs.

Threaded Elbow

Threaded elbow consists of a screw mouth, bending part, etc. Its characteristics depend on the external thread groove above the screw mouth, in the piping system software, threaded elbow is to change the orientation of the pipe fittings.
The working pressure of the threaded elbow is: 2000LB, 3000LB, 6000LB.
The key manufacturing standards for threaded elbows are generally GB/T14383, ASMEB16.11, BS3799.

Two types of threaded elbows are available as mentioned below:

Threaded 90° Elbow: These Elbows are used for a 90° changes of direction in the run of pipe.

Threaded 45° Elbow: These threaded Elbows help the main pipe to make a 45° direction change.

Dimensions Threaded Elbows 90°/45° ASME B16.11

thd elb 90 45 dim1 - What are threaded pipe fittings

Class 2000
NPS Min Thread Length Outside Dia Min WT Center to End
B J D G 90° 45°
A C
1/2 10.9 13.6 33 3.18 28 22
3/4 12.7 13.9 38 3.18 33 25
1 14.7 17.3 46 3.68 38 28
1.1/4 17 18 56 3.89 44 33
1.1/2 17.8 18.4 62 4.01 51 35
2 19 19.2 75 4.27 60 43
2.1/2 23.6 28.9 92 5.61 76 52
3 25.9 30.5 109 5.99 86 64
4 27.7 33 146 6.55 106 79
Class 3000
NPS Min Thread Length Outside Dia Min WT Center to End
B J D G 90° 45°
A C
1/2 10.9 13.6 38 4.09 33 25
3/4 12.7 13.9 46 4.32 38 28
1 14.7 17.3 56 4.98 44 33
1.1/4 17 18 62 5.28 51 35
1.1/2 17.8 18.4 75 5.56 60 43
2 19 19.2 84 7.14 64 44
2.1/2 23.6 28.9 102 7.65 83 52
3 25.9 30.5 121 8.84 95 64
4 27.7 33 152 11.18 114 79
Class 6000
NPS Min Thread Length Outside Dia Min WT Center to End
B J D G 90° 45°
A C
1/2 10.9 13.6 46 8.15 38 28
3/4 12.7 13.9 56 8.53 44 33
1 14.7 17.3 62 9.93 51 35
1.1/4 17 18 75 10.59 60 43
1.1/2 17.8 18.4 84 11.07 64 44
2 19 19.2 102 12.09 83 52
2.1/2 23.6 28.9 121 15.29 95 64
3 25.9 30.5 146 16.64 106 79
4 27.7 33 152 18.67 114 79

General notes..

  • Dimensions are in millimeters unless otherwise indicated.
  • Dimension (B) is minimum length of perfect thread.
    The length of useful thread (B plus threads with fully formed roots and flat crests) shall not be less than J.

Threaded Cross

20220620145210 44342 - What are threaded pipe fittings

Threaded elbow consists of a screw mouth, bending part, etc. Its characteristics depend on the external thread groove above the screw mouth, in the piping system software, threaded elbow is to change the orientation of the pipe fittings.

The working pressure of the threaded elbow is: 2000LB, 3000LB, 6000LB.

The key manufacturing standards for threaded elbows are generally GB/T14383, ASMEB16.11, BS3799.

Threaded Cross Dimensions – ASME B16.11

Threaded Cross Drawing.jpg - What are threaded pipe fittings

Threaded Cross Drawing

DN Nom. Center to End Center to End Outside Diameter Minimum Wall Length Of
Pipe Elbow,Tee,Cross 45°Elbow Of Band Thickness Thread
Size A C H G Min.(1)
  2000 3000 6000 2000 3000 6000 2000 3000 6000 2000 3000 6000 B L2
6 1/8″ 21 21 25 17 17 19 22 22 25 3.18 3.18 6.35 6.4 6.7
8 1/4″ 21 25 28 17 19 22 22 25 33 3.18 3.3 6.6 8.1 10.2
10 3/8″ 25 28 33 19 22 25 25 33 38 3.18 3.51 6.98 9.1 10.4
15 1/2″ 28 33 38 22 25 28 33 38 46 3.18 4.09 8.15 10.9 13.6
20 3/4″ 33 38 44 25 28 33 38 46 56 3.18 4.32 8.53 12.7 13.9
25 1″ 38 44 51 28 33 35 46 56 62 3.68 4.98 9.93 14.7 17.3
32 1-1/4″ 44 51 60 33 35 43 56 62 75 3.89 5.28 10.59 17 18
40 1-1/2″ 51 60 64 35 43 44 62 75 84 4.01 5.56 11.07 17.8 18.4
50 2″ 60 64 83 43 44 52 75 84 102 4.27 7.14 12.09 19 19.2
65 2-1/2″ 76 83 95 52 52 64 92 102 121 5.61 7.65 15.29 23.6 28.9
80 3″ 86 95 106 64 64 79 109 121 146 5.99 8.84 16.64 25.9 30.5
100 4″ 106 114 114 79 79 79 146 152 152 6.55 11.18 18.67 27.7 33
  • Dimensions in Millimeters
  • Dimension B is minimum length of perfect thread. The length of useful thread (B plus threads with fully formed roots and flat crests) shall not be less than L2 (effective length of external thread) required by American National Standard for Pipe Threads (ANSI/ASME B1.20.1)

Threaded Tee

Threaded Tee as pipe fitting makes a perpendicular branch from the main pipe run. They are available in two types:

Threaded Equal Tee: Main pipe and Branch pipe size are equal.

Threaded Reducing Tee: Branch Pipe Size is smaller than main pipe.

Threaded Tee.jpg - What are threaded pipe fittings

Threaded Tee Dimensions – ASME B16.11

Threaded Tee Drawing.jpg - What are threaded pipe fittings

Threaded Tee Drawing

DN Nom. Center to End Center to End Outside Diameter Minimum Wall Length Of
Pipe Elbow,Tee,Cross 45°Elbow Of Band Thickness Thread
Size A C H G Min.(1)
  2000 3000 6000 2000 3000 6000 2000 3000 6000 2000 3000 6000 B L2
6 1/8″ 21 21 25 17 17 19 22 22 25 3.18 3.18 6.35 6.4 6.7
8 1/4″ 21 25 28 17 19 22 22 25 33 3.18 3.3 6.6 8.1 10.2
10 3/8″ 25 28 33 19 22 25 25 33 38 3.18 3.51 6.98 9.1 10.4
15 1/2″ 28 33 38 22 25 28 33 38 46 3.18 4.09 8.15 10.9 13.6
20 3/4″ 33 38 44 25 28 33 38 46 56 3.18 4.32 8.53 12.7 13.9
25 1″ 38 44 51 28 33 35 46 56 62 3.68 4.98 9.93 14.7 17.3
32 1-1/4″ 44 51 60 33 35 43 56 62 75 3.89 5.28 10.59 17 18
40 1-1/2″ 51 60 64 35 43 44 62 75 84 4.01 5.56 11.07 17.8 18.4
50 2″ 60 64 83 43 44 52 75 84 102 4.27 7.14 12.09 19 19.2
65 2-1/2″ 76 83 95 52 52 64 92 102 121 5.61 7.65 15.29 23.6 28.9
80 3″ 86 95 106 64 64 79 109 121 146 5.99 8.84 16.64 25.9 30.5
100 4″ 106 114 114 79 79 79 146 152 152 6.55 11.18 18.67 27.7 33
  • Dimensions in Millimeters
  • Dimension B is minimum length of perfect thread. The length of useful thread (B plus threads with fully formed roots and flat crests) shall not be less than L2 (effective length of external thread) required by American National Standard for Pipe Threads (ANSI/ASME B1.20.1)

Threaded Couplings

Threaded couplings are forged fittings for joining pipes. They are available as full couplings or half couplings.

Dimensions Threaded Full and Half Couplings ASME B16.11

thd couplings1 - What are threaded pipe fittings

Class 3000
NPS Length Outside Dia Min Thread Length
A D B J
1/2 48 28 10.9 13.6
3/4 51 35 12.7 13.9
1 60 44 14.7 17.3
1.1/4 67 57 17 18
1.1/2 79 64 17.8 18.4
2 86 76 19 19.2
2.1/2 92 92 23.6 28.9
3 108 108 25.9 30.5
4 121 140 27.7 33
Class 6000
NPS Length Outside Dia Min Thread Length
A D B J
1/2 48 38 10.9 13.6
3/4 51 44 12.7 13.9
1 60 57 14.7 17.3
1.1/4 67 64 17 18
1.1/2 79 76 17.8 18.4
2 86 92 19 19.2
2.1/2 92 108 23.6 28.9
3 108 127 25.9 30.5
4 121 159 27.7 33

General notes..

  • Dimensions are in millimeters unless otherwise indicated.
  • Dimension (B) is minimum length of perfect thread.
    The length of useful thread (B plus threads with fully formed roots and flat crests) shall not be less than J.

Threaded Cap

Threaded caps are used to close or cover piping ends. So threaded piping caps (Fig. 5) are used for sealing purposes.

Threaded Cap.jpg - What are threaded pipe fittings

Threaded Pipe Cap Dimensions – ASME B16.11

Threaded Pipe Cap Drawing.jpg - What are threaded pipe fittings

Threaded Pipe Cap Drawing

DN Nom. Center to End Center to End Outside End Wall Length Of
Pipe Coupling Cap Diameter Thickness Thread
Size W P D G Min. Min.(1)
  3000&6000 3000 6000 3000 6000 3000 6000 B L2
6 1/8″ 32 19 16 4.8 6.4 6.7
8 1/4″ 35 25 27 19 25 4.8 6.4 8.1 10.2
10 3/8″ 38 25 27 22 32 4.8 6.4 9.1 10.4
15 1/2″ 48 32 33 28 38 6.4 7.9 10.9 13.6
20 3/4″ 51 37 38 35 44 6.4 7.9 12.7 13.9
25 1″ 60 41 43 44 57 9.7 11.2 14.7 17.3
32 1-1/4″ 67 44 46 57 64 9.7 11.2 17 18
40 1-1/2″ 79 44 48 64 76 11.2 12.7 17.8 18.4
50 2″ 86 48 51 76 92 12.7 15.7 19 19.2
65 2-1/2″ 92 60 64 92 108 15.7 19 23.6 28.9
80 3″ 108 65 68 108 127 19 22.4 25.9 30.5
100 4″ 121 68 75 140 159 22.4 28.4 27.7 33
  • Dimensions in Millimeters.
  • Dimension B is minimum length of perfect thread. The length of useful thread (B plus threads with fully formed roots and flat crests) shall not be less than L2(effective length of external thread) required by American National Standard for Pipe Threads ANSI/ASME B1.20.1)

Threaded Plugs

Threaded plugs are also used for sealing or blinding purposes. they are available in three variants:

  • Threaded Square Head Plug: The shape of the head is square.
  • Threaded Hex Head Plug: The shape of the head is hexagonal.
  • Threaded Round Head Plug: The shape of the head is circular.

Threaded Square Head Plug Dimensions – ASME B16.11

Threaded Square Head Plug Drawing.jpg - What are threaded pipe fittings

Threaded Square Head Plug Drawing

DN Nom. Length Square Head Plug Round Head Plug Hex.Head Plug&Bushing
Pipe (Min) Height of Width Flat Nominal Length Width Flat Hex.Height (Min.
Size A Square (Min.) Diameter (Min.) (Nom.)
    (Min.) C of Head (Nom) E F Bushing Plug
    B   D     G H
6 1/8″ 10 6 7 10 35 6
8 1/4″ 11 6 10 14 41 16 3 6
10 3/8″ 13 8 11 18 41 18 4 8
15 1/2″ 14 10 14 21 44 22 5 8
20 3/4″ 16 11 16 27 44 27 6 10
25 1″ 19 13 21 33 51 36 6 10
32 1-1/4″ 21 14 24 43 51 46 7 14
40 1-1/2″ 21 16 28 48 51 50 8 16
50 2″ 22 18 32 60 64 65 9 18
65 2-1/2″ 27 19 36 73 70 75 10 19
80 3″ 28 21 41 89 70 90 10 21
100 4″ 32 25 65 114 76 115 13 25
  • Dimensions in Millimeters
  • Cautionary note regarding Hex Bushing – Hex head bushing if one-size reduction should not be used in services where they might be subject to harmful loads and forces other than internal pressure.

Threaded Hexagon Head Plug Dimensions – ASME B16.11

Threaded Hexagon Head Plug Drawing.jpg - What are threaded pipe fittings

Threaded Hexagon Head Plug Drawing

DN Nom. Length Square Head Plug Round Head Plug Hex.Head Plug&Bushing
Pipe (Min) Height of Width Flat Nominal Length Width Flat Hex.Height (Min.
Size A Square (Min.) Diameter (Min.) (Nom.)
    (Min.) C of Head (Nom) E F Bushing Plug
    B   D     G H
6 1/8″ 10 6 7 10 35 6
8 1/4″ 11 6 10 14 41 16 3 6
10 3/8″ 13 8 11 18 41 18 4 8
15 1/2″ 14 10 14 21 44 22 5 8
20 3/4″ 16 11 16 27 44 27 6 10
25 1″ 19 13 21 33 51 36 6 10
32 1-1/4″ 21 14 24 43 51 46 7 14
40 1-1/2″ 21 16 28 48 51 50 8 16
50 2″ 22 18 32 60 64 65 9 18
65 2-1/2″ 27 19 36 73 70 75 10 19
80 3″ 28 21 41 89 70 90 10 21
100 4″ 32 25 65 114 76 115 13 25
  • Dimensions in Millimeters
  • Cautionary note regarding Hex Bushing – Hex head bushing if one-size reduction should not be used in services where they might be subject to harmful loads and forces other than internal pressure.

Threaded Round Head Plug Dimensions – ASME B16.11

Threaded Round Head Plug Drawing.jpg - What are threaded pipe fittings

Threaded Round Head Plug Drawing

DN Nom. Length Square Head Plug Round Head Plug Hex.Head Plug&Bushing
Pipe (Min) Height of Width Flat Nominal Length Width Flat Hex.Height (Min.
Size A Square (Min.) Diameter (Min.) (Nom.)
    (Min.) C of Head (Nom) E F Bushing Plug
    B   D     G H
6 1/8″ 10 6 7 10 35 6
8 1/4″ 11 6 10 14 41 16 3 6
10 3/8″ 13 8 11 18 41 18 4 8
15 1/2″ 14 10 14 21 44 22 5 8
20 3/4″ 16 11 16 27 44 27 6 10
25 1″ 19 13 21 33 51 36 6 10
32 1-1/4″ 21 14 24 43 51 46 7 14
40 1-1/2″ 21 16 28 48 51 50 8 16
50 2″ 22 18 32 60 64 65 9 18
65 2-1/2″ 27 19 36 73 70 75 10 19
80 3″ 28 21 41 89 70 90 10 21
100 4″ 32 25 65 114 76 115 13 25
  • Dimensions in Millimeters
  • Cautionary note regarding Hex Bushing – Hex head bushing if one-size reduction should not be used in services where they might be subject to harmful loads and forces other than internal pressure.

Threaded Cap

Threaded Pipe Cap are used as a protective device to protect pipe ends. The main purpose of using ANSI B16.11 Forged Threaded Pipe Cap is to waterproof the connections. 3000LB Threaded Pipe Cap are also used to close the the ends of hydraulic or pneumatic pipes and tubes.

Threaded Pipe Cap Dimensions – ASME B16.11

Threaded Pipe Cap Drawing.jpg - What are threaded pipe fittings

Threaded Pipe Cap Drawing

DN Nom. Center to End Center to End Outside End Wall Length Of
Pipe Coupling Cap Diameter Thickness Thread
Size W P D G Min. Min.(1)
  3000&6000 3000 6000 3000 6000 3000 6000 B L2
6 1/8″ 32 19 16 4.8 6.4 6.7
8 1/4″ 35 25 27 19 25 4.8 6.4 8.1 10.2
10 3/8″ 38 25 27 22 32 4.8 6.4 9.1 10.4
15 1/2″ 48 32 33 28 38 6.4 7.9 10.9 13.6
20 3/4″ 51 37 38 35 44 6.4 7.9 12.7 13.9
25 1″ 60 41 43 44 57 9.7 11.2 14.7 17.3
32 1-1/4″ 67 44 46 57 64 9.7 11.2 17 18
40 1-1/2″ 79 44 48 64 76 11.2 12.7 17.8 18.4
50 2″ 86 48 51 76 92 12.7 15.7 19 19.2
65 2-1/2″ 92 60 64 92 108 15.7 19 23.6 28.9
80 3″ 108 65 68 108 127 19 22.4 25.9 30.5
100 4″ 121 68 75 140 159 22.4 28.4 27.7 33
  • Dimensions in Millimeters.
  • Dimension B is minimum length of perfect thread. The length of useful thread(B plus threads with fully formed roots and flat crests)shall not be less than L2(effective length of external thread) required by American National Standard for Pipe Threads ANSI/ASME B1.20.1)

Threaded Bushings

Threaded bushings have hexagonal heads and are used for joining to threaded pipes of different size. So, threaded bushing can aid in size reduction.

Threaded Hexagon Head Bushing Dimensions – ASME B16.11

Threaded Hexagon Head Bushing Drawing.jpg - What are threaded pipe fittings

Threaded Hexagon Head Bushing Drawing

DN Nom. Length Square Head Plug Round Head Plug Hex.Head Plug&Bushing
Pipe (Min) Height of Width Flat Nominal Length Width Flat Hex.Height (Min.
Size A Square (Min.) Diameter (Min.) (Nom.)
    (Min.) C of Head (Nom) E F Bushing Plug
    B   D     G H
6 1/8″ 10 6 7 10 35 6
8 1/4″ 11 6 10 14 41 16 3 6
10 3/8″ 13 8 11 18 41 18 4 8
15 1/2″ 14 10 14 21 44 22 5 8
20 3/4″ 16 11 16 27 44 27 6 10
25 1″ 19 13 21 33 51 36 6 10
32 1-1/4″ 21 14 24 43 51 46 7 14
40 1-1/2″ 21 16 28 48 51 50 8 16
50 2″ 22 18 32 60 64 65 9 18
65 2-1/2″ 27 19 36 73 70 75 10 19
80 3″ 28 21 41 89 70 90 10 21
100 4″ 32 25 65 114 76 115 13 25
  • Dimensions in Millimeters
  • Cautionary note regarding Hex Bushing – Hex head bushing if one-size reduction should not be used in services where they might be subject to harmful loads and forces other than internal pressure.

Threaded Flush Bushing Dimensions – ASME B16.11

Threaded Flush Bushing Drawing.jpg - What are threaded pipe fittings

Threaded Hexagon Head Bushing Drawing

DN Nom. Length Square Head Plug Round Head Plug Hex.Head Plug&Bushing
Pipe (Min) Height of Width Flat Nominal Length Width Flat Hex.Height (Min.
Size A Square (Min.) Diameter (Min.) (Nom.)
    (Min.) C of Head (Nom) E F Bushing Plug
    B   D     G H
6 1/8″ 10 6 7 10 35 6
8 1/4″ 11 6 10 14 41 16 3 6
10 3/8″ 13 8 11 18 41 18 4 8
15 1/2″ 14 10 14 21 44 22 5 8
20 3/4″ 16 11 16 27 44 27 6 10
25 1″ 19 13 21 33 51 36 6 10
32 1-1/4″ 21 14 24 43 51 46 7 14
40 1-1/2″ 21 16 28 48 51 50 8 16
50 2″ 22 18 32 60 64 65 9 18
65 2-1/2″ 27 19 36 73 70 75 10 19
80 3″ 28 21 41 89 70 90 10 21
100 4″ 32 25 65 114 76 115 13 25
  • Dimensions in Millimeters
  • Cautionary note regarding Hex Bushing – Hex head bushing if one-size reduction should not be used in services where they might be subject to harmful loads and forces other than internal pressure.

Threaded Unions

Threaded unions are designed based on MSS-SP 83. Threaded unions consist of three interconnected elements and used for installation and maintenance purposes. Unions are available in the male to female, female to female types, lug nut, and Rockwood design. The lug nut connected both the pieces.

Threaded Union Dimensions – MSS-SP 83

Threaded Union Drawing.jpg - What are threaded pipe fittings

Threaded Union Drawing

Nom. Pipe End Wall Water Male Nut Threads Bearing Length Clear
Pipe Way Bore Flange Per Assem. Assem.
Size     25.4mm Nom. Nut
  Min.A Min.C D Min.F Min.G Max.H Min.J L N
1/8″ 14.7 2.41 8.43 3.18 3.18 16 1.24 41.4 50.8
6.43
1/4″ 19 3.02 11.13 3.18 3.18 16 1.24 41.4 50.8
9.45
3/8″ 22.9 3.2 14.27 3.43 3.43 14 1.37 46 55.9
13.51
1/2″ 27.7 3.73 17.86 3.68 3.68 14 1.5 49 58.4
17.07
3/4″ 33.5 3.91 23.01 4.06 4.06 11 1.68 56.9 66
21.39
1″ 41.4 4.55 28.98 4.57 4.45 11 1.85 62 78.7
27.74
1-1/4″ 50.5 4.85 37.69 5.33 5.21 11 2.13 71.1 94
35.36
1-1/2″ 57.2 5.08 43.54 5.84 5.59 10 2.31 76.5 111.8
41.2
2″ 70.1 5.54 55.58 6.6 6.35 10 2.69 86.1 132.1
52.12
2-1/2″ 85.3 7.01 66.27 7.49 7.11 8 3.07 102.4 149.9
64.31
3″ 102.4 7.62 88.25 8.26 8 8 3.53 109 175.3
77.27
  • Dimensions in Millimeters.
  • Upper and lower values for each size are the respective maximum and minimum dimensions.

Use of threaded pipe fittings

Threaded fittings are not suitable for higher pressures and temperatures and for cyclic operation. Therefore, they are used in the following less critical low-voltage environments:

  • Fire Fighting System
  • Water distribution system
  • Cooling systems
  • Piping systems, etc.

Threaded connections are also mostly used for the connection between tubes and their components with DN ≤ 40. They are often used where welding is not suitable or where disassembly is required. There are male threads (Male Screw) and female threads (Female Screw) for threaded connections. Among the common fittings, threaded short joints are male threads, while elbows, tees, caps, and fittings are mostly female threads, so attention should be paid to the combination between them when they are used. Compared with welding, threaded connections have low joint strength and poor sealing performance, so their use is often limited by the following conditions.

  • (1) Threaded connections of fittings should be tapered pipe threads.
  • (2) Threaded connections are not recommended for use at temperatures greater than 200°C and lower than -45°C.
  • (3) Threaded connections shall not be used on highly toxic media piping.
  • (4) According to the national standard GB50316, threaded connections shall not be used in fluid conditions with crevice corrosion, and should not be used in the pipeline with vibration.
  • (5) When used on combustible gas pipeline, it is appropriate to use sealing welding for sealing.

What is the difference between NPS, NPT and NPTF?

  • NPS = National Pipe Straight
  • NPT = National Pipe Thread
  • NPTF = National Pipe Thread Fuel

NPT and NPS have the same thread angle, shape and pitch (number of threads per inch). However, NPT threads are tapered and NPS threads are straight (parallel). Both threads have a 60° angle and have flat crests and valleys. Tapered pipe threads are typically found on the ends of pipes, fittings and accessories (e.g. couplings, elbows, tees, etc.).
Sharp threads are critical to ensure tight, leak-free joints. A thread sealant or tape is usually required to complete the seal. Straight pipe threads require a gasket or O-ring to create a seal. Although NPT and NPS threads will engage, they will not properly seal against each other.
20220619000305 81447 - What are threaded pipe fittings

NPT vs. NPTF

  • The requirements of NPT (National Pipe Thread) are detailed in ANSI B1.20.1
  • The requirements of NPTF (National Pipe Thread Fuel) are detailed in ANSI B1.20.3

NPT and NPTF have the same threads per inch, median diameter and taper per inch. The differences are in the major and minor diameters, root and top of the threads.
NPTF thread crests conform to the parameters required by NPT, but have a smaller range than NPT.
The NPTF thread root differs from the NPT thread root. the NPTF thread root is designed to interfere with the top of the mating thread and is intended to create a mechanical seal through thread deformation during assembly. the NPTF thread has two identified classes: Class 1 and Class 2. the NPT thread root is designed to allow clearance from the mating thread crest on the assembly.

Headers – NPT and NPS

While NPT and NPS threads will engage and appear to fit, they will not seal properly against each other, resulting in leaks.
Creating a leak-free NPT connection requires the use of thread sealing tape.
National Pipe Tapered Fuel (NPTF), also known as dry seal American National Standard Tapered Pipe Threads, as defined by ASME B1.20.3, are designed to provide a more leak-free seal without the use of PTFE tape (aka “Teflon”) or other sealants. root height is adjusted for interference fit, eliminating the spiral leak path.

Sizes of Threaded

These threaded pipe fittings are available in sizes from 1/8 to 6 inches, so you can build a system that works for your needs.

  • Threaded pipe fittings are designed for use with residential and commercial plumbing systems.

  • The connection between the male threaded fitting and the female threaded fitting is permanent once they’re locked together, but they’re easy to remove if necessary.

What are thread dimensions?

The thread size is given as a nominal size, not as an actual measurement. For example, when a screw or bolt has a size of 5.9 mm, it is referred to as a 6 mm thread. There are two common ways to write thread sizes.
1. Thread sizes in inches are specified by diameter and threads per inch. For example, in screw sizes 10-24, the first number refers to the thread diameter and the second number is the number of threads per inch (TPI). When the diameter is less than 1/4″, the value is indicated by a number, such as #1 or No. 1.

thread size in inch - What are threaded pipe fittings

2. Thread sizes in metric are specified by diameter and pitch. The metric thread sizes are generally expressed as M2 × 0.25, the thread diameter is 2mm and pitch is 0.25mm.
Thread Dimensions – Imperial Thread Sizes Chart
Here are two imperial thread sizes table defines thread dimensions of coarse threads (UNC/UNRC) and fine threads (UNF/UNRF). All units in inches.
Coarse Thread Sizes

coarse thread size chart - What are threaded pipe fittings

Fine Thread Sizes

fine thread size chart - What are threaded pipe fittings

Thread Dimensions – Metric Thread Sizes Chart
Here is the metric thread sizes table defines standard metric external thread size M1.6 to M18 per. ANSI/ASME B1.13M-1995. All units in mm. 
Fittings for Threaded Pipe systems
Various threaded fittings are available for threaded piping systems. They are:Metric Thread Sizes Chart - What are threaded pipe fittings

What is Tolerance for Threaded Fittings?

ASME B16.11 Dimensional Tolerances

Engineering Specifications for Socket Weld Fittings Manufactured Per ASME B16.11-2001.

weldgap - What are threaded pipe fittingsforgdim - What are threaded pipe fittingsbardim - What are threaded pipe fittings

DIMENSIONAL TOLERANCES PERMITTED UNDER THIS AMERICAN STANDARD ASME B16.11-2001

“A” – CENTER TO BOTTOM OF SOCKET FOR SIZES ± 0.03″
1/8″ AND 1/4″
3/8″, 1/2″ AND 3/4″ ± 0.06″
1″, 1-1/4″, 1-1/2″ AND 2″ ± 0.08″
2-1/2″, 3″, AND 4″ ± 0.10″
“B” – BORE DIAMETER OF SOCKET FOR SIZES + 0.020″
1-1/2″ AND SMALLER – 0.000″
2″, 2-1/2″, 3″ AND 4″ + 0.025″
– 0.000″
“C” – SOCKET WALL THICKNESS MINIMUM = 1.09 T (BUT NOT LESS THAN 5/32″)
T = WALL THICKNESS OF NOMINAL PIPE
“D” – BORE DIAMETER OF FITTING FOR SIZES ± 0.030″
2″ AND SMALLER
2-1/2″, 3″ AND 4″ ± 0.060″
“E” – BOTTOM TO BOTTOM OF SOCKETS – COUPLINGS FOR SIZES ± 0.06″
1/8″ AND 1/4″
3/8″, 1/2″ AND 3/4″ ± 0.12″
1″, 1-1/4″, 1-1/2″ AND 2″ ± 0.16″
2-1/2″, 3″, AND 4″ ± 0.20″
“F” – BOTTOM OF SOCKET TO OPPOSITE FACE – HALF COUPLINGS FOR SIZES ± 0.03″
1/8″ AND 1/4″
3/8″, 1/2″ AND 3/4″ ± 0.06″
1″, 1-1/4″, 1-1/2″ AND 2″ ± 0.08″
2-1/2″, 3″, AND 4″ ± 0.10″
“G” – WELDING GAP APPROXIMATELY 0.06″
RECOMMENDED GAP BEFORE WELDING
“H” – MINIMUM FLAT MINIMUM FLAT = 0.75 X MINIMUM
SOCKET WALL THICKNESS

How is threaded fitting size measured?

For general standard threads, thread ring gauges or plug gauges are used for measurement.
Since there are many thread parameters, it is not possible to measure each and every parameter of the thread, so we usually use thread gauges (thread ring gauges and thread plug gauges) to make a comprehensive determination of the thread. This method is not only convenient and reliable, but also has the same accuracy requirements as ordinary threads, so it has become the most common method of acceptance in actual production.

20220619222825 29065 - What are threaded pipe fittings

Thread ring gauges or plug gauges

5 steps to determine thread type and pipe size

1. What are you going to do with this joint?
Suppose you live in Europe and buy an NPT for your coffee machine. However, you don’t realize that your coffee machine is made in Italy and requires BSP threaded joints. If you try to screw the NPT thread to the BSP, you will damage the thread on the machine. In many cases, this damage is irreparable.
If your device does not display the thread type, you cannot judge whether your device is NPT or BSP only by observing the thread. If you live in the United States, you may need NPT. If you live in Europe, you may need BSP. You can always measure the thread or test different types of fittings to find the type you need.
2. Do you need a male or female connector?
Threads have one sex — either male or female. The thread is outside the male joint and inside the female joint. The outer diameter of the external thread is smaller than that of the internal thread because one end of the external thread is pressed into one end of the internal thread.
3. Is the thread tapered or straight?
NPs refers to national straight pipe and NPT refers to national tapered pipe. Tapered threads become narrower as they extend outward, while straight threads maintain the same diameter.
The body of the straight pipe joint has no taper and is sealed with another joint with an O-ring or gasket. Both male and female joints have a conical flare at the end to enable them to be screwed together and form a tight seal. When the male and female heads are screwed together, the threads lock with each other.
Both straight and tapered joints need to be sealed to prevent leakage. The outer end of the straight pipe joint must be sealed with an O-ring, gasket or gasket. Tapered joints shall be sealed with Teflon tape, pipe coating or some other pipe sealant.
You must have the right partner to ensure that your connection is sound. If you try to screw a tapered joint into a straight pipe joint, you can only get a few thread depths. Although the joint looks as if it is tightly attached, the sealing is not strong enough to prevent leakage.
4. What is the thread size or pipe size of the joint?
Measuring the thread size of a pipe is the most confusing part for many homeowners, because the thread size is not based on standard measurement units. The thread size is based on the inside diameter of the pipe. Use a caliper, tape measure, or ruler to measure the thread diameter of the external or internal thread. Measure the inner diameter (ID) of the internal thread and the outer diameter (OD) of the external thread. This number will help determine the size of the thread.
Measure the outside diameter of the thread measure the inside diameter of the joint
After measuring the thread on the joint, you must match this number with the thread diagram to determine the nominal size. Thread size and pipe size are measured in the same proportion.
5. What couplings are compatible?
Choosing the pipe joint you need is like choosing the right LEGO toy when building LEGO toys. Your project will determine the arrangement of your accessories. If you want to go around the back of the cabinet to find the ice maker, or want to hide the pipe, you should avoid leakage points. Where you need to send water, liquid, or air — around a corner or up a pipe — determines the shape or style of fittings to use.
Note: there are many joints, bends or elbows that may cause pressure loss and slow flow.
Material problems. Putting different metals together may cause corrosion. The material of the joint and O-ring or gasket must be chemically compatible with the substance that will flow through it.

Skills of assembling pipe fittings

Do not cross through your threads. If you feel that a connector enters incorrectly when you insert it, it is a cross thread or an angle.
Use teflon tape instead of pipe paint to seal the threads for easier installation. The pipe glue may be messy. If you use it too much, it may flow into your filter housing or equipment. After using the sealant, make sure you test the seal to make sure it is effective.
Clean both ends of your accessories before use. You don’t want debris trapped in the threads.
Do not over tighten, which may cause the joint to crack or split. This is especially problematic when using plastic fittings.

The difference between fractional and metric threaded joints

We can find many different types and specifications of transition joints in the market. Among the many types of joints, the more used ones are metric threaded joints and imperial threaded joints. However, when many friends select and use them, it is easy to confuse these two types of joints together, in fact, there are not small differences between the two.
1. From the specifications of the use of units
Inch joints, from the name, we can roughly know that its diameter specification unit is used in inches, the same, the pitch specification unit in the identification, the number of teeth per inch is also used. The diameter of metric joints is in millimeters, and the pitch is in metric lengths.
2. From the point of view of the diameter of the joint
The diameter of the screw head of the standard imperial connector seen on the market is 9.3MM, while that of the metric connector is 9.7MM, so the screw head diameter of the imperial connector is smaller than that of the metric connector.
3. From the point of view of appearance
The appearance of the connector is often different for different sizes. For a simple example, if it is an F-type joint, we can observe that the imperial joint will have a small step, while the metric joint has a flat surface and no step. Also, the shape of the outer opening of the nut of an imperial fitting is usually cylindrical, while the shape of the outer opening of a metric fitting nut is square hexagonal.
4. From the point of view of applicable standards
Generally speaking, metric joints use domestic standards, while imperial joints use international standards.
5. From the perspective of threads
The thread style of metric fittings is internal thread, while the thread style of imperial fittings is external thread.
6. From the point of view of production
Most of the metric joints are produced in China, while imperial joints are not only produced in China, but also abroad.
Joints are widely used in industrial production, especially in pipeline connections, which are commonly used as connecting elements. In order to let you better apply the joint, let’s understand what are its uses? What do you need to pay attention to in the process of use?
1. Use
The main function of this joint is to connect two different types of pipes, especially in the field of telecommunication and electricity. For example, when laying a pipeline, because the pipeline material is hard and cannot be bent, you can use this joint to connect two pipes, so that the effect of bending can be realized.
2. Cautions for use
In the process of installing the joint, it should be necessary to determine whether the caliber of the pipe is the same as the caliber of the joint, and when installing it, attention should be paid to good anti-leakage and anti-corrosion measures. Regardless of whether the pipeline is transported inside the liquid or gas, or to protect the cable fiber, should take into account the sealing, in the sealing is guaranteed at the same time, should not forget the anti-corrosion treatment.

From the above, we can know that although the metric and imperial threaded joints have a transitional role, there are still great differences and distinctions between the two, so when using them, do not mix the two, especially in recent years with the development of the joint industry, the market demand for joints has increased significantly, if the difference between the two joints can be clearly distinguished, you can avoid a lot of unnecessary trouble.

How to make threaded pipe fittings

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Process flow diagram of threaded pipe fittings
I. Raw material re-inspection
The surface of raw materials should be free of oil and dirt, and should not be allowed to contact with low melting point metals (Cu, Zn, Sn, Pb, etc.) during handling, loading and unloading, otherwise they should be removed by appropriate methods (such as sandblasting).
Materials for pipe fittings include metal materials such as forgings, bars or seamless tubes, etc. The materials used are rechecked to determine that the metal materials meet the technical requirements of the order and the chemical composition requirements specified in the relevant material standards.
Raw materials should have quality certificate, no mark, no batch number, no quality certificate or incomplete quality certificate items cannot be used.
II. Material
Select the type of raw materials according to the specifications of the produced pipe fittings, and number the blanks to make records.
III. Manufacturing 
Set aside the amount of machining, the material should be forged as close as possible to the specified shape and size to reduce processing costs.
Cylindrical products can be made from hot-rolled or forged bars or seamless tube cutting process, the axial direction of the product should be roughly parallel to the rolling direction of the metal billet. Should not be manufactured by direct cutting and processing of bars.
IV. Heat treatment
Normally, for cold forming or hot forming of carbon steel should be annealed or normalized heat treatment.
When the manufacturing conditions meet the following requirements, heat treatment may not be carried out.

  • a) The final forging temperature of carbon steel fittings is not less than 700 ℃ and not more than 980 ℃, and placed under the conditions of cooling in still air.
  • b) Directly with the bar or seamless pipe cutting and manufacturing of pipe fittings, and the material has been factory heat-treated or carbon steel materials for the hot-rolled state.

V. Machining
Strictly in accordance with GB/T 14383-2008 standard requirements for mechanical processing. Geometric dimensions and limit deviations should meet the requirements of the standard.
The threads of threaded fittings should conform to the 60° tapered pipe thread (NPT) in ASME B16.11 standard. When the purchaser specifies other thread types, the thread type and standard number should be indicated in the order.
VI. Size and appearance inspection
The shape and dimensional tolerances of forged threaded pipe fittings shall conform to the requirements of AS ME B16.11 standard.
The surface of forged threaded fittings should be inspected piece by piece and should be free of cracks, laminations and other defects, and should be free of burrs, oxide and other adhesions. 
The surface of the pipe fittings are allowed to have scattered but not large areas of scars, folds, pits, hairlines, scratches, etc., but their depth should not be greater than 5% of the wall thickness and not more than 0.8mm.
The surface scars, folds, pits, hairlines, scratches, etc. that exceed the depth specified in 6.3 should be polished and removed, and the wall thickness of the polished area should not be less than the minimum value specified.
VII. Non-destructive testing
Each piece of pipe before nondestructive testing, the internal and external surfaces of the pipe should be wiped clean. And to ensure that the surface roughness to meet the testing requirements.
Nondestructive testing personnel should be assessed by GB/T9445 or other equivalent standards, and nondestructive testing should be conducted by I, II or III personnel. The evaluation of the display results should be carried out by I-level personnel under the supervision of II and III-level personnel, or directly by II and III-level personnel.
For all forged threaded pipe fittings the entire body of the pipe according to JB4730 for 100% magnetic particle, magnetic particle testing selected A-30/100 or C-15/50 standard test piece, level I qualified.
VIII. Marking

  • Marking position

Each pipe fitting should be wrought with raised letters, steel printing, engraving or electro-etching and other permanent marking methods, the end of the pipe fitting flange or projection position marked clearly visible signs; cylindrical pipe fittings should be marked in the outer diameter or in the welding installation of the logo will not disappear after the end. When using steel markings, should not make the imprint invade the minimum wall thickness of the pipe body. 

  • Marking content

The marking of pipe fittings should include the following.

  • 1) Manufacturer’s name or trademark. 
  • 2) material grade.
  • 3) material melting furnace number.  
  • 4) pipe fittings level. 
  • 5) Nominal size.
  • 6) Standard number (may not include the age number).
  • 7) other markings required by the contract.

If the size of the pipe fittings can not be marked out all the contents of the logo, can be omitted in the opposite order, but at least the manufacturer’s name or trademark and material grade should be marked out two content, while the additional label should be marked out in the form of the full logo content.
IX. Packing of threaded pipe fittings
The fittings are packed in carton firstly, then in plywood box /pallets for sea and air shipment. If you have any specific, please tell us when you order.

Quality Control of threaded pipe fittings

Our forged threaded pipe fittings will be inspected before shipment, including non-destructive testing (PT, MT or ut test), dimensional inspection and PMI test. The chemical analysis and mechanical performance test are carried out according to the heat number, and the corrosion test and other inspections are carried out according to the customer’s requirements.
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PMI test for forged threaded pipe fittings

How to order threaded pipe fittings

When you want to get a quote or release a PO to us, pls clear the information:
Fittings type + End type ( NPT/BSP or SW) + Class + Size + Material + Standard + Order Quantity
For example, you want to buy 60 pcs 90 Elebow 6000# TH 2” for your system in stainless steel 316, the piping design is to ASME, so the description would be:

  • 90 Threaded Elbow, 2” 6000#, A182 F316, ASME B16.11, 60PCS

How to purchase threaded fittings

1. Determine the type of threaded fitting you need. There are many options to choose from, including couplings, elbows, adapters and tees.
Before you start your search for the perfect threaded fitting, it’s important to determine what kind of fitting will best suit your needs. There are many types of threaded fittings to choose from, including couplings, elbows, adapters and tees.
To determine what type of fitting you need:

  • Determine exactly how many threads (and at what distance apart) are required by measuring the length between supports and measuring how far apart they are from each other.
  • Decide if a male or female connection is needed based on whether there is already something attached at either end of the pipe line (this will help prevent any compatibility issues).
  • Consider where the pipe line will be located — indoors or outdoors? If outdoors (or in an area where dust may collect), consider using stainless steel fittings because these hold up better in harsh conditions than standard galvanized ones do.

2. Choose a material that fits your needs. Your options include stainless steel, carbon steel, galvanized steel and brass or bronze.
To get the best fit for your situation, it’s important to choose a material that fits your needs. Your options include plastic, steel, galvanized steel and brass or bronze. Plastic fittings are used in low-pressure applications like irrigation systems. Steel is used in high-pressure applications such as fire sprinkler systems while brass or bronze fittings are used in high-pressure applications such as fire sprinkler systems where corrosion resistance is necessary.
3. Select a size that corresponds with your application. Most fittings are available in sizes ranging from 1/8″ to 4″, although these sizes can vary based on the type of fitting you choose.
To get the best fit for your situation, it’s important to choose a material that fits your needs. Your options include plastic, steel, galvanized steel and brass or bronze. Plastic fittings are used in low-pressure applications like irrigation systems. Steel is used in high-pressure applications such as fire sprinkler systems while brass or bronze fittings are used in high-pressure applications such as fire sprinkler systems where corrosion resistance is necessary.
4. Find a versatile option like a reducing bushing, which is designed to attach two dissimilar pipes.
To get the best fit for your situation, it’s important to choose a material that fits your needs. Your options include plastic, steel, galvanized steel and brass or bronze. Plastic fittings are used in low-pressure applications like irrigation systems. Steel is used in high-pressure applications such as fire sprinkler systems while brass or bronze fittings are used in high-pressure applications such as fire sprinkler systems where corrosion resistance is necessary.
5. Choose a threaded fitting designed for use in high-pressure settings, such as those found in oil and gas industries or on commercial building sites.
To get the best fit for your situation, it’s important to choose a material that fits your needs. Your options include plastic, steel, galvanized steel and brass or bronze. Plastic fittings are used in low-pressure applications like irrigation systems. Steel is used in high-pressure applications such as fire sprinkler systems while brass or bronze fittings are used in high-pressure applications such as fire sprinkler systems where corrosion resistance is necessary.
6. Choosing the right threaded fitting involves selecting the right material and size for your specific application.

To get the best fit for your situation, it’s important to choose a material that fits your needs. Your options include plastic, steel, galvanized steel and brass or bronze. Plastic fittings are used in low-pressure applications like irrigation systems. Steel is used in high-pressure applications such as fire sprinkler systems while brass or bronze fittings are used in high-pressure applications such as fire sprinkler systems where corrosion resistance is necessary.

Where To Buy Threaded fittings?

Find a reliable selection platform
The more important thing about the selection of threaded pipe fittings nowadays is that it makes everyone get lost in the selection process. In this case, our choice of this pipe can be distinguished based on their brand. The products, reputation and strength of different brands vary from industry to industry. So you can understand the influence of the first brand in the industry, and then dock the platform to purchase can make their purchase process smoother, and also avoid buying fake threaded pipe fittings.
Choose products from big companies
Threaded fittings are more widely used in life, including some national enterprises and large enterprises, which also need to apply threaded fittings. When you don’t know how to choose, you can follow these large companies to choose. These companies have a general shopping list when it comes to purchasing items. You can go to the brand-name companies to choose the products to purchase, and generally there will not be much problem.
Don’t just go for cheap when buying products
When it comes to cheap, it’s a word that many people can say freely. But in the actual purchasing process, everyone can be easily attracted by the low price. But threaded fittings have their own standard prices, so if you come across a market with low prices for threaded fittings, suspect that there is something wrong with the pipe. Instead of trying to buy much cheaper, for example, leaving yourself with hidden problems.
Analysis of the service life of threaded fittings
Of course, some users do not like to try new products, thinking that new products are too expensive, the price is relatively low. In fact, we use some products with long-term vision, such as product durability, which is a very important factor for us to buy products. Traditional pipes may only last three to five years, but threaded fittings last 10 years. If you calculate the cost of time, maybe you’ll see why threaded fittings are the most cost-effective.
Mastering these methods can help you buy easily when buying threaded pipe from a pit. To say something more popular, if you want to buy authentic quality threaded pipe, first of all, you have to look for big brands, and then the basic ability of price discrimination of this product, it can help people to buy more threaded pipe.

Conclusion

As you can see, there are many types of threaded pipe fittings that can be used to join pipes together. If you have any questions about which type of fitting is best for your application, please check out our blog post on the subject or contact us.

Source: China Threaded Pipe Fittings Manufacturer – Yaang Pipe Industry (www.epowermetals.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at [email protected]

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