What is a fastener
What are Fasteners Solutions?
Table of Contents
- What are Fasteners Solutions?
- What is a fastener?
- Characteristics of fasteners
- Materials of Fasteners
- Types of Fasteners
- Standard of fasteners
- Uses of Fasteners
- Identification and inspection of threads
- Types and structure of steel structure bolts
- Manufacturing process of fasteners
- Packing of fasteners
- Quality inspection of fasteners
- Measurement of fasteners
- How to improve the quality of fasteners
- Cost of fasteners
- How to Choose Industrial Fasteners
- How to find reliable fastener manufacturers
- Place an order of fastener
Fastener solutions refer to the various types of devices, products, and techniques used to join or secure materials together. These solutions play a crucial role in numerous industries, including construction, automotive, aerospace, and manufacturing.
What is a fastener?
Fastener is an important hardware device, which is used in many engineering related applications to mechanically connect or fix two or more objects together. They are considered as alternatives to welding. Also known as standard parts on the market.
In the manufacturing of machines, fasteners are used to hold two parts together. Fasteners can also be divided into three categories: permanent fasteners, temporary fasteners and semi-permanent fasteners.
Characteristics of fasteners
Fasteners are mechanical devices that hold two or more parts together. They can be assembled and disassembled at will, allowing for easy removal of the parts without damaging them. Fasteners are generally small in size, light in weight and easy to mass produce. This allows manufacturers to use large quantities of fasteners on a single assembly line with minimal labor costs compared to other types of fastener systems. Additionally, their ease of use means they require little maintenance and therefore have low operating costs over time compared with other systems such as rivets or bolts which require frequent maintenance due to their complexity.”
Materials of Fasteners
There are three main types of steel fasteners used in industry: stainless steel, carbon steel and alloy steel. Main grades of stainless steel fasteners: 200 series, 300 series and 400 series. Titanium, aluminum and various alloys are also common structural materials of metal fasteners. In many cases, special coatings or coatings can be applied to metal fasteners to improve their performance characteristics, such as enhancing corrosion resistance. Common coatings / coatings include zinc, chromium and hot dip galvanizing.
Carbon steel
Carbon steel is a series of carbon and iron alloys, containing up to about 1% carbon and up to 1.65% manganese, and adding a specific amount of deoxidizing elements and residues of other elements.
Low alloy steel
Low alloy steel is a kind of metal mixture composed of steel and other metals, which has ideal properties. Low alloy steel contains about 1% – 5% alloy elements. Therefore, it has precise chemical composition, provides better mechanical properties and aims to prevent corrosion.
Stainless steel
Stainless steel is a general term of the corrosion-resistant alloy steel family containing 10.5% or more chromium. All stainless steels have high corrosion resistance. This resistance to attack is due to the formation of a natural chromium rich oxide film on the surface of the steel.
Brass
Brass is a copper-based alloy with the main addition being zinc.
Aluminum
Aluminum is a silvery white metal and the 13th element in the periodic table. A surprising fact about aluminum is that it is the most widely distributed metal on earth, accounting for more than 8% of the mass of the earth’s core. It is also the third most common chemical element on our planet after oxygen and silicon.
Copper
Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a malleable metal with very high thermal conductivity and conductivity. Pure copper is soft and plastic; The newly exposed surface is orange red. It is used as a conductor of heat and electricity, building materials, and components of various metal alloys.
The title was provided by our writer.
Titanium
Titanium is a transition metal light with white silver metal color. It is strong, shiny and corrosion resistant. Pure titanium is insoluble in water, but soluble in concentrated acid. When exposed to high temperatures in the air, this metal forms a passive but protective oxide layer (resulting in corrosion resistance), but it can resist discoloration at room temperature.
The main oxidation state is 4+, although the states of 3+ and 2+ are also known, but they are not very stable. This element burns in air when it is heated to obtain dioxide TiO2 and when it combines with halogen. It reduces water vapor to form carbon dioxide and hydrogen. It reacts in a similar way to hot concentrated acid, but it forms trichloride with chlorohydric acid. The metal absorbs hydrogen to obtain TiH2 and forms nitride tin and carbide tic. Other known compounds are sulfur TiS2, the lowest oxides Ti2O3 and TiO, and sulfur Ti2S3 and tis. Salts are known in all three oxidation states.
Nickel and its alloys
Nickel alloy is an alloy with nickel as the main element. There is complete solid solubility between nickel and copper. The wide solubility range between iron, chromium and nickel makes many alloy combinations possible.
All these materials can be found on a variety of fastener types including screws, rivets, bolts and nuts. They are used in both structural applications as well as non-structural applications such as fastening accessories to furniture or electronic devices
Types of Fasteners
There are many types of fasteners. The following is a list of the most common:
1. Bolt: it is a fastener composed of head and cylinder, and the screw has external thread. It needs to be used with nuts to fasten and connect two parts with through holes. Bolted connections are removable connections.
2. Stud: it is a fastener without head, and only two ends have external threads. When connecting, one end must be screwed into the part with internal thread hole, the other end must pass through the part with through hole, and then screw on the nut, even if the two parts are closely connected as a whole. Stud connection is also a detachable connection.
3. Screw: it is also a fastener composed of head and screw.
According to the purpose, it can be divided into three categories: mechanical screw, fixed screw and special purpose screw.
- 1) Mechanical screw: mainly used for fastening connection between parts with fixed threaded holes and parts with through holes.
- 2) Fixing screw: mainly used to fix the relative position between two parts.
- 3) Special purpose screws: for example, there are eyebolts for lifting parts.
4. Nut: it has internal thread hole shape, generally flat hexagonal column shape, flat square column shape or flat cylindrical shape. It is used in conjunction with bolts, studs or machine screws to fasten and connect two parts into a whole.
According to its special category, it is divided into two categories: high-strength self-locking nut and nylon self-locking nut.
- 1) High strength self-locking nut: high strength and good reliability. It is used for road construction machinery, mining machinery, vibration machinery and equipment. It is European technology and less domestic production.
- 2) Nylon self-locking nut. It is a new type of high seismic and anti loosening fastener, which can be used in various electromechanical products with a temperature of – 50100 ℃. The demand for nylon self-locking nuts in aerospace, aviation, tanks, mining machinery, automobile transportation machinery, agricultural machinery, textile machinery, electrical products and all kinds of machinery has increased sharply, which can prevent major accidents caused by loose fasteners.
5. Self tapping screw: similar to machine screw, but the thread on the screw is the special thread of self tapping screw. It is used to fasten and connect two thin metal components as a whole. This connection is also a detachable connection.
6. Wood screw: it is also similar to machine screw, but the thread on the screw is the special thread of wood screw, which can be directly screwed on wood parts or parts to connect metal or non-metal parts with through holes with wood screws. These parts are fixed together. This connection is also a removable connection.
7. The shape of the washer is a fastener ring. It is placed between the support surface of the bolt, screw or nut and the surface of the connector, which increases the contact surface area of the connector, reduces the pressure per unit area, and protects the surface of the connector from damage. Another elastic washer can also play such a role. It has the function of preventing the nut from loosening.
8. Retaining ring: installed in the shaft groove or hole groove of machinery and equipment to prevent the left and right movement of parts on the shaft or hole.
9. Pin: it is mainly used for the positioning of parts, and some are also used for the connection of parts, fixing parts, transmitting power or locking other fasteners.
10. Rivet: it is a fastener composed of head and handle. It is used to fasten and connect two parts or components with through holes to make them a whole. This connection form is called rivet connection, or riveting for short. It is an inseparable connection.
11. Assembly and connection sub assembly: refers to a combination of supplied fasteners, such as some machine screws or bolts, self provided screws, flat washers or spring washers, and lock washers are supplied in combination. Connecting pair: refers to a fastener supplied by a combination of special bolts, nuts and washers, such as high-strength hexagon head bolt connecting pair for steel structure.
12. Welding nail: it is a heterogeneous fastener composed of light energy and nail head or no nail head, which is fixedly connected to a part or component by welding for connection with other parts.
13. Steel wire screw sleeve: it is a new type of threaded connection element, which is refined from high-strength and high-precision corrosion-resistant diamond wire. Shaped like a spring, it is installed in a specific screw hole of the matrix, and its inner surface forms a standard thread. Matching with the screw bolt can significantly improve the strength and wear resistance of the threaded connection; Especially in aluminum, magnesium, cast iron, plastics and other low-strength materials. The locking type is to add one or more locking rings on the basis of the ordinary type.
Standard of fasteners
The following table is provided for guidance only as there are often dimensional variations between standards.
DIN Standard | ISO Standard | British Standard | Product |
---|---|---|---|
DIN 1 | ISO 2339 | Cone Pins, untempered | |
DIN 125 | ISO 7089 | Washers; medium type, primarily for hexagon bolts | |
DIN 125 | ISO 7090 | Washers; medium type, primarily for hexagon bolts | |
DIN 126 | ISO 7091 | Product grade C washers – designed for use with Hexagon Head Bolts and Nut | |
DIN 127 | BS4464B | Spring Lock Washers with square ends or tang ends | |
DIN 128 | Curved and wave Spring Lock Washers | ||
DIN 137 | Spring Washers, curved or wave | ||
DIN 1440 | ISO 8738 | Medium type washers for pins | |
DIN 1443 | ISO 2340 | Clevis Pins without head | |
DIN 1444 | ISO 2341 | Clevis Pins with head | |
DIN 1470 | ISO 8739 | Grooved Pins, full length parallel-grooved with pilot | |
DIN 1471 | ISO 8744 | Grooved Pins, full length taper-grooved | |
DIN 1472 | ISO 8745 | Grooved Pins, half length taper-grooved | |
DIN 1473 | ISO 8740 | Grooved Pins, full length parallel-grooved with chamfer | |
DIN 1474 | ISO 8741 | Grooved Pins, half length reverse-grooved | |
DIN 1475 | ISO 8742 | Grooved Pins, third length centre-grooved | |
DIN 1476 | ISO 8746 | Round Head Grooved Pins | |
DIN 1477 | ISO 8747 | Countersunk Head Grooved Pins | |
DIN 1481 | ISO 8752 | Spring-type Straight Pins (roll pins) – heavy type | |
DIN 1587 | Hexagon Domed Cap Nuts | ||
DIN 1816 | Round Nut with set pin holes inside; ISO metric fine thread | ||
DIN 315 | Wing Nuts with rounded wings | ||
DIN 316 | Wing Screws with rounded wings | ||
DIN 404 | Slotted Capstan Screws | ||
DIN 417 | ISO 7435 | Slotted Set Screws with long dog point | |
DIN 427 | ISO 2342 | Slotted Headless Screws with chamfered end | |
DIN 428 | ISO 4034 | Hexagon Nuts, Grade C | |
DIN 433 | ISO 7092 | Washers for use with cheese head screws | |
DIN 433-1 | ISO 7092 | Product grade A washers – with a hardness up to 250 HV designed for use with cheese head screws | |
DIN 433-2 | ISO 7092 | Product grade A washers – with a hardness up to 300 HV designed for use with cheese head screws | |
DIN 438 | ISO 7436 | Slotted Set Screws with cup point | |
DIN 439 | ISO 4035 | BS3692 | Hexagon Thin Nuts |
DIN 439 | ISO 4036 | BS3692 | Hexagon Thin Nuts |
DIN 439 | ISO 8675 | BS3692 | Hexagon Thin Nuts |
DIN 439-1 | ISO 4036 | Unchamfered Hexagon Thin Nuts – product grade B | |
DIN 439-2 | ISO 4035 | Chamfered Hexagon Thin Nuts – product grades A and B | |
DIN 439-2 | ISO 8675 | Chamfered Hexagon Thin Nuts – product grades A and B | |
DIN 440 | ISO 7094 | Washers for use in timber constructions | |
DIN 444 | Eyebolts | ||
DIN 462 | Machine tools; internal tab washers for slotted round nuts for hook spanner according to DIN 1804 | ||
DIN 464 | Knurled Thumb Screws, high type | ||
DIN 466 | Knurled Nuts, high type | ||
DIN 467 | Knurled Nuts, low type | ||
DIN 471 | Circlips (retaining rings) for shafts; normal type and heavy type | ||
DIN 479 | Square Head Bolts with short dog point | ||
DIN 5406 | Lock Washers and locking plates for use with rolling bearings | ||
DIN 548 | Round Nuts with set pin holes inside | ||
DIN 551 | ISO 4766 | Slotted Set Screws with flat point | |
DIN 553 | ISO 7434 | Slotted Set Screws with cone point | |
DIN 555 | ISO 4034 | M5 to M100x6 Hexagon Nuts – product grade C | |
DIN 558 | ISO 4018 | Hexagon Head Screws | |
DIN 580 | Collar Eyebolts for lifting purposes | ||
DIN 601 | ISO 4016 | M5 to M52 Hexagon Head Bolts; product grade C | |
DIN 603 | Mushroom Head Square Neck Bolts | ||
DIN 609 | Hexagon Fits Bolts with long thread | ||
DIN 6319 | Spherical Washers and conical seats | ||
DIN 6325 | ISO 8734 | Parallel Pins, hardened: tolerance zone m6 | |
DIN 6340 | Washers for clamping devices | ||
DIN 653 | Knurled Thumb Screws, low type | ||
DIN 6797 | Toothed Lock Washers | ||
DIN 6798 | Serrated Lock Washers | ||
DIN 6799 | Lock Washers (retaining washers) for shafts | ||
DIN 6900 | ISO 10644 | Screw and Washer assemblies | |
DIN 6901 | ISO 10510 | Tapping Screw and Washer assemblies | |
DIN 6902 | ISO 10673 | Plain Washers for screw and washer assemblies | |
DIN 6903 | ISO 10669 | Plain Washers for tapping screw and washer assemblies | |
DIN 6912 | Hexagon Socket Thin Head Cap Screws with pilot recess | ||
DIN 6914 | ISO 14399-4 | High-strength Hexagon Head Bolts with large widths across flats for structural steel bolting | |
DIN 6916 | Round Washers for high-strength structural steel bolting | ||
DIN 6921 | ISO 1665 | Hexagon Flange Bolts | |
DIN 6922 | ISO 1665 | Hexagon Flange Bolts with reduced shank | |
DIN 6923 | ISO 1661 | Hexagon Nuts with flange | |
DIN 6924 | ISO 7040 | Prevailing torque type Hexagon Nuts with non-metallic insert | |
DIN 6924 | ISO 10512 | Prevailing torque type Hexagon Nuts with non-metallic insert | |
DIN 6925 | ISO 7042 | Prevailing torque type all-metal Hexagon Nuts | |
DIN 6925 | ISO 10513 | Prevailing torque type all-metal Hexagon Nuts | |
DIN 6926 | ISO 7043 | Prevailing torque type Hexagon Nuts with flange and with non-metallic insert | |
DIN 6926 | ISO 12125 | Prevailing torque type Hexagon Nuts with flange and with non-metallic insert | |
DIN 6927 | ISO 7044 | Prevailing torque type All-Metal Nuts with flange | |
DIN 6927 | ISO 12126 | Prevailing torque type All-Metal Nuts with flange | |
DIN 7045 | Pan Head Screws with type H or type Z cross recess – product grade A | ||
DIN 7337 | ISO 14589 | Break mandrel Bblind Rivets | |
DIN 7337 | ISO 15977 to ISO 15984 | Break mandrel Blind Rivets | |
DIN 7337 | ISO 16582 to ISO 16584 | Break mandrel Blind Rivets | |
DIN 7343 | ISO 8750 | Spiral Pins; normal type | |
DIN 7344 | ISO 8748 | Spiral Pins; heavy duty type | |
DIN 7346 | ISO 13337 | Spring-type Straight Pins; (roll pins) lightweight type | |
DIN 7349 | Plain Washers for Bolts with heavy clamping sleeves | ||
DIN 7500-1 | ISO 7085 | Thread rolling Screws for metric ISO thread – Part 1: Types, designation, requirements | |
DIN 7500-2 | Thread rolling Screws for ISO metric thread; guideline values for hole diameters | ||
DIN 7504 | Self-drilling Screws with tapping screw thread – dimensions, requirements and testing | ||
DIN 7513 | Hexagon Head and slotted head thread cutting screws – dimensions, requirements and testing | ||
DIN 7516 | Cross recessed head thread cutting screws – dimensions, requirements and testing | ||
DIN 7603 | Ring Seals and Gaskets | ||
DIN 7970 | ISO 1478 | Threads and thread ends for tapping screws (modified version of ISO 1478) | |
DIN 7971 | ISO 1481 | BS4174 | Slotted Pan Head Tapping Screws |
DIN 7972 | ISO 1482 | Slotted Countersunk Head Tapping Screws | |
DIN 7973 | ISO 1483 | Slotted Raised Countersunk Head Tapping Screws | |
DIN 7977 | ISO 8737 | Taper Pins with thread ends and constant point lengths | |
DIN 7978 | ISO 8736 | Taper Pins with internal thread | |
DIN 7979 | ISO 8733 | Parallel Pins with internal thread | |
DIN 7979 | ISO 8735 | Parallel Pins with internal thread | |
DIN 7980 | BS4464A | Spring Lock Washers with square ends for cheese head screws | |
DIN 7981 | ISO 7049 | Cross Recessed Pan Head Tapping Screws | |
DIN 7982 | ISO 7050 | Cross Recessed Countersunk Head Tapping Screws | |
DIN 7983 | ISO 7051 | Countersunk (flat) Head Tapping Screws with cross recess | |
DIN 7984 | Hexagon Socket Thin Head Cap Screws | ||
DIN 7985 | ISO 7045 | BS4183 | Cross recessed raised Phillips Pan Head Screws |
DIN 7989-1 | Washers for steel structures – product grade C | ||
DIN 7989-2 | Washers for steel structures – product grade A | ||
DIN 7991 | ISO 10642 | BS4168 | Hexagon Socket Countersunk Head Cap Screws |
DIN 84 | ISO 1207 | BS4183 | Product grade A Slotted Cheese Head Screws |
DIN 85 | ISO 1580 | BS4183 | Product grade A Slotted Pan Head Screws |
DIN 9021 | ISO 7093 | Plain Washers with large outside diameter | |
DIN 908 | Hexagon Socket Screw Plugs with parallel screw thread | ||
DIN 910 | Hexagon-duty hexagon Head Screw Plugs | ||
DIN 911 | ISO 2936 | Hexagon Socket Screw Keys | |
DIN 912 | ISO 4762 | BS4168 | Hexagon Socket Head Cap Screws (modified version of ISO 4762) |
DIN 912 | ISO 21268 | BS4168 | Hexagon Socket Head Cap Screws (modified version of ISO 4762) |
DIN 913 | ISO 4026 | Hexagon Socket Set Screws with flat point (ISO 4026 modified) | |
DIN 914 | ISO 4027 | Hexagon Socket Set Screws with cone point (ISO 4029 modified) | |
DIN 915 | ISO 4028 | Hexagon Socket Set Screws with full dog point | |
DIN 916 | ISO 4029 | Hexagon Socket Set Screws with cup point (ISO 4029 modified) | |
DIN 918-3 | Overview of European standards for fasteners | ||
DIN 921 | Slotted Pan Head Screws with large head | ||
DIN 923 | Slotted Pan Head Screws with shoulder | ||
DIN 929 | Hexagon Weld Nuts | ||
DIN 93 | Tab Washers with long tab | ||
DIN 930 | Fine thread pitch partially Threaded Screws | ||
DIN 931-1 | ISO 4014 | BS3692 | M1,6 to M39 Hexagon Cap Screws partially threaded – product grades A and B |
DIN 931-2 | ISO 4014 | BS3692 | M42 to M160x6 Hexagon Cap Screws partially threaded – product grade B |
DIN 933 | ISO 4017 | BS3692 | M1,6 to M52 Hexagon Cap Screws fully threaded – product grades 8.8 |
DIN 934 | ISO 4032 | Hexagon Nuts with metric coarse and fine pitch thread – product classes A and B | |
DIN 934 | ISO 8673 | Hexagon Nuts with metric coarse and fine pitch thread – product classes A and B | |
DIN 935-1 | Hexagon Slotted Nuts and Castle Nuts with metric coarse and fine pitch thread – product grades A and B | ||
DIN 935-2 | M42 to M160x6 Hexagon Head Bolts; product grade B | ||
DIN 935-3 | Hexagon Slotted Nuts with metric coarse pitch thread – product grade C | ||
DIN 936 | BS3692 | M8 to M52 and M8x1 to M52x3 hexagon thin nuts; product grades A and B | |
DIN 937 | Hexagon Thin Castle Nuts | ||
DIN 938 | Studs with a length of engagement equal to about 1 d | ||
DIN 939 | Studs with a length of engagement equal to about 1,25 d | ||
DIN 94 | ISO 1234 | Split Pins | |
DIN 95 | Slotted Raised Countersunk (oval) Head Wood Screws | ||
DIN 96 | Slotted Round Head Wood Screws | ||
DIN 960 | ISO 8765 | M8x1 to M100x4 Hexagon Head Bolts with fine pitch thread – product grades A and B | |
DIN 960 | ISO 8676 | M8x1 to M100x4 Hexagon Head Bolts with fine pitch thread – product grades A and B | |
DIN 961 | ISO 8676 | M8x1 to M52x3 Hexagon Head Bolts with fine pitch thread – product grades A and B | |
DIN 962 | Designation system for fasteners | ||
DIN 963 | ISO 2009 | BS3692 | Slotted Countersunk Head Screws (with countersunk heads as specified in ISO 2009-1972) |
DIN 964 | ISO 2010 | BS3692 | Slotted Raised Countersunk Oval Head Screws |
DIN 965 | ISO 7046 | BS3692 | Cross Recessed Countersunk Flat Head Screws |
DIN 966 | ISO 7047 | Cross Recessed Raised Countersunk Head Screws | |
DIN 970 | ISO 4032 | Hexagon Nuts; style 1; metric coarse thread, product grades A and B; ISO 4032 modified | |
DIN 971-1 | ISO 8673 | Style 1 Hexagon Nuts with metric fine pitch thread; property classes 6 and 8 | |
DIN 971-2 | ISO 8674 | Style 2 Hexagon Nuts with metric fine pitch thread; property classes 10 and 12 | |
DIN 972 | ISO 4034 | M5 to M39 Hexagon Nuts; style 1; product grade C (modified version of ISO 4034) | |
DIN 975 | Threaded Rods | ||
DIN 976-1 | Metric thread Stud Bolts | ||
DIN 976-2 | Metric interference-fit thread Stud Bolts | ||
DIN 977 | ISO 21670 | Hexagon Weld Nuts with flange | |
DIN 979 | Hexagon Thin Slotted Nuts and Castle Nuts with metric coarse and fine pitch thread – Product grades A and B | ||
DIN 980 | ISO 7042 | All-metal prevailing torque type Hexagon Nuts | |
DIN 980 | ISO 10513 | All-metal prevailing torque type Hexagon Nuts | |
DIN 981 | Locknuts for use with rolling bearings | ||
DIN 982 | ISO 7040 | Prevailing torque type Hexagon Nuts with non-metallic insert | |
DIN 982 | ISO 10512 | Prevailing torque type Hexagon Nuts with non-metallic insert | |
DIN 983 | Retaining Rings with lugs for use on shafts (external circlips) | ||
DIN 985 | ISO 10511 | Prevailing torque type Hexagon Thin Nuts with non-metallic insert | |
DIN 986 | Prevailing torque type Hexagon Domed Cap Nuts with non-metallic insert | ||
DIN 988 | Shim Rings and supporting rings |
Uses of Fasteners
Fasteners are used in applications where holding power is required.Fasteners are mechanical units used to connect two or more objects. Fasteners can be used for permanent or temporary connections, depending on site conditions. There are many types of fasteners that have different applications and people should certainly know.
Fasteners can be divided into permanent or temporary units.
Examples of permanent fasteners can be rivets, nails, etc., which are disposable fasteners designed to permanently connect two objects. Therefore, these fasteners cannot be removed once installed, and removing it may cause damage to it. Temporary fasteners are designed to temporarily connect two or more objects and can be easily removed and reused.
Examples of temporary fasteners are bolts and screws, which are commonly used in some industries and products because they allow components to be reassembled when needed. Temporary fasteners are also called threaded or unthreaded.
From household appliances commonly used in our daily life to some high-tech gadgets, we all have a common component, that is fasteners. Although fasteners are not directly imagined by us, they will play an important role in our routine life. Whatever it is, from the tables and chairs we sit on to the cars we travel, because every edge we use is fixed in place by fasteners. Fasteners can be used in various industries, such as automobile, petrochemical, pharmaceutical, oil and natural gas, rubber, food processing, heavy machinery and so on.
Identification and inspection of threads
The use and characteristics of threads.
Threads are used in a wide range of applications, from airplanes and automobiles to water pipes and gas used in our daily lives, most threads are used for fastening connections, followed by force and motion transmission, and some specialized threads.
The use of threads has endured because of their simple structure, reliable performance, ease of disassembly and ease of manufacture, making them an indispensable structural element in various electromechanical products today.
According to the use of threads, all kinds of threaded parts should have the following two basic functions: first, good spinability; second, sufficient strength.
Classification of threads
a. There are four major categories according to their structural characteristics and uses:
- Common thread (fastening thread): The thread is triangular in shape and is used to connect or fasten parts. The common thread is divided into coarse thread and fine thread according to the pitch, and the connection strength of fine thread is higher.
- Transmission threads: The threads are trapezoidal, rectangular, saw-shaped and triangular in shape.
- Sealing threads: Used for sealing connections, mainly pipe threads, tapered threads and tapered pipe threads.
- Special-purpose threads, referred to as special threads.
b. Threads can be divided into metric threads (metric threads), English threads, American threads, etc. We customarily refer to English threads and American threads collectively as English threads, which have a tooth angle of 60°, 55°, etc. The thread parameters such as diameter and pitch use the English size (inch). In our country, the thread angle is 60°, and the diameter and pitch in millimeters (mm) are used.
Basic terminology of threads
- Thread: A continuous protrusion with a specified thread pattern along the spiral line on a cylindrical or conical surface.
- External thread: The thread formed on the external surface of a cylinder or cone.
- Internal thread: The internal thread formed on the inner surface of a cylinder or cone.
- Major diameter: The diameter of an imaginary cylinder or cone tangent to the top of the male thread or the bottom of the female thread.
- Minor diameter: The diameter of an imaginary cylinder or cone tangent to the bottom of the external thread or the top of the internal thread.
- Median: The diameter of an imaginary cylinder or cone whose bus bar passes through a groove and a projection of equal width on the tooth pattern. This hypothetical cylinder or cone is called a median cylinder or median cone.
- Right-hand thread: A thread that is screwed in when rotated clockwise.
- Left-hand thread: A thread that is screwed in when rotated counterclockwise.
- Tooth angle: The angle between two adjacent tooth sides on a thread tooth pattern.
- Pitch: The axial distance between two points on the mid-diameter line of two adjacent teeth.
Marking of threads
Metric thread markings:
In general, a complete metric thread marking should include the following three aspects:
- a. The thread type code indicating the characteristics of the thread;
- b. Thread size: Generally, the diameter and pitch should be included, and for multi-threads, the lead and thread number should be included;
- c. Accuracy of the thread: The accuracy of most threads is determined by the tolerance zone (including the position and size of the tolerance zone) of each diameter and the length of the spin.
Thread measurement
For standard threads, the thread ring gauge or plug gauge is used to measure the thread.
Since there are many thread parameters, it is impossible to measure each one of them individually. It is convenient and reliable, and has become the most common method of acceptance in actual production because it is comparable to the accuracy requirements of ordinary threads.
Thread measurement (middle diameter)
In a threaded connection, only the median size determines the nature of the thread fit, so it is critical to determine whether the median size is properly qualified. Based on the fact that the median size should ensure that the most basic performance of the thread is achieved, the standard stipulates the principle of judging the median qualification, namely: “The actual thread’s operational median cannot exceed the median of the largest solid tooth type. And the single median diameter of any part of the actual thread cannot exceed the median diameter of the smallest solid tooth type.”
There are two convenient methods to measure the single mid-diameter, one is to measure the mid-diameter with a thread mid-diameter micrometer, and the other is to use the three-pin method (our company uses the three-pin method).
Thread fit grade
The thread fit is the size of loose or tight between the screwed threads, and the grade of the fit is the combination of deviation and tolerance specified on the internal and external threads.
(1) For unified imperial threads, there are three thread grades for external threads: 1A, 2A and 3A, and three grades for internal threads: 1B, 2B and 3B, all of which are clearance fits. The higher the grade number, the tighter the fit. In imperial threads, deviations are specified only for grades 1A and 2A, with zero deviation for grade 3A, and the deviations are equal for grades 1A and 2A.
The larger the grade number the smaller the tolerance, as shown in the figure:
- 1) Class 1A and 1B, very loose tolerance grades, which are applicable to the tolerance fit of internal and external threads.
- 2) Class 2A and 2B, the most common thread tolerance class specified for imperial series mechanical fasteners.
- 3) Grades 3A and 3B, the tightest fit for tight tolerance fasteners, are used for safety-critical designs.
- 4) For external threads, Class 1A and 2A have a fit deviation, while Class 3A does not. Class 1A tolerance is 50% greater than Class 2A tolerance and 75% greater than Class 3A, and for internal threads, Class 2B tolerance is 30% greater than 2A tolerance. Class 1B is 50% greater than Class 2B and 75% greater than Class 3B.
(2) For metric threads, there are common thread grades for external threads: 4h, 6e, 6g and 6h, and for internal threads: 6G, 6 H and 7H. (Japanese standard thread accuracy grades are divided into three levels: I, II and III, and the usual condition is grade II.) In metric threads, the basic deviation of H and h is zero. the basic deviation of G is positive, and the basic deviation of e, f and g is negative. As shown in the figure:
- 1) H is a common tolerance zone position for internal threads, and is not generally used as a surface coating or with a very thin phosphate layer. g position basic deviation is used for special occasions, such as thicker coatings, and is generally rarely used.
- 2) g is commonly used to plating 6-9um thin plating, such as product drawings require 6h bolt, its thread before plating using the tolerance band of 6g.
- 3) The thread fit is best combined as H/g, H/h or G/h. For the thread of refined fasteners such as bolts and nuts, the standard recommendation is to use a 6H/6g fit.
Medium accuracy grade for common threads
Nut: 6H
Bolt: 6g
Medium accuracy grade for threads with thick cover
Nuts: 6G Bolts: 6e
High-precision grade
Nuts: 4H Bolts: 4h , 6h
Types and structure of steel structure bolts
Steel Structure Bolt Connection
Steel structure bolting is a connection method to connect two or more steel structure parts or members with bolts to become one. Bolt connection is the easiest way to connect the components in pre-assembly and structural installation.
Bolted connections were first used in the installation of metal structures, and in the late 1830s, bolted connections were gradually replaced by riveted connections, which were only used as temporary fixing measures in the assembly of members. high strength bolting methods emerged in the 1950s. High-strength bolts are made of medium carbon steel or medium carbon alloy steel, and their strength is 2-3 times higher than ordinary bolts. High-strength bolt connection has the advantages of easy construction, safety and reliability, and began to be used in the manufacture and installation of steel structures in some metallurgical plants after the 1960s.
Specifications of bolts
Bolt specifications commonly used in steel structures are M12, M16, M20, M24, M30, M is the bolt symbol, the number is the nominal diameter.
Bolts in accordance with the performance level of 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9, 12.9 a total of ten grades, of which more than 8.8 grade bolt material for low-carbon alloy steel or medium carbon steel and heat treatment (quenching, tempering), commonly known as high-strength bolts, 8.8 grade below (excluding 8.8 grade, refined ordinary bolts also contain 8.8 grade) Generally known as ordinary bolts. The following table shows the performance grade and mechanical properties of bolts.
The bolt performance grade number consists of two parts, which indicate the nominal tensile strength of the bolt and the flexural strength ratio of the material. Such as the performance level of 4.6 bolts means: the first part of the number (“4” in 4.6) for the nominal tensile strength of the bolt material (N/mm2) 1/100, that is, fu ≥ 400N/mm2; the second part of the number (“6” in 4.6) “) for the bolt material yield strength ratio of 10 times, that is, fy/fu = 0.6; the product of the two parts of the number (4 × 6 = “24”) for the nominal yield point (or yield strength) of the bolt material (N/mm2) of 1/10, that is, fy ≥ 240N/mm2.
Ordinary bolts of steel structure can be divided into three grades according to the production accuracy: A, B and C. A and B grade are refined bolts, which are generally used for mechanical products, and C grade are rough bolts. Unless otherwise specified, ordinary bolts of steel structure are generally ordinary rough-made C grade bolts with performance grade 4.6 or 4.8.
The strength design value of the bolt connection using GB50017-2003 “Steel Design Code” Table 3.4.1-4 take value.
The classification of bolts
Bolts in a broad sense, including ordinary bolts, high-strength bolts, foot anchors, expansion bolts, chemical anchors, screws, pins, etc.; bolts in a narrow sense are divided into ordinary bolted connections and high-strength bolts.
1) Ordinary bolt connection
Ordinary bolts are divided into rough bolts and fine bolts according to the production accuracy.
Ordinary bolts can be divided into hexagonal head bolts, double head bolts, countersunk head bolts according to the form.
Rough bolts
C-level bolts are generally rough bolts, made of carbon structural steel. In order to make the bolts penetrate into the screw holes smoothly, the aperture should be 1.0-2.0mm larger than the nominal diameter d of the bolts, which is a class II hole. The bolt hole spacing arrangement should be convenient for the wrench to tighten the nut. When the rough bolt is used to connect the members of the column, beam and roof frame, the connection structure with the pallet should be used. At this time, the bolt is in tension and the shear force is carried by the pallet (as shown below).
The low strength grade of the material used in the rough bolt limits the scope of its use in the structural connection, but it is still widely used in the connection of the secondary beam of the working platform, the wall skin beam, the roof beam and the support, the articulated support, etc., where the shear force is small.
Rough bolts are also commonly used for pre-assembly of steel structures in plants, pre-tightening of riveted members before riveting, and temporary tightening before assembly and welding of installation nodes before high-strength bolts are connected. When rough bolts are used as permanent fixing bolts, they need to be tightened and anti-loosening measures taken after alignment.
Refined bolts
Grade A and B bolts are refined bolts, and the holes are generally Class I. The aperture should be 0.3-0.5mm larger than the nominal diameter of the bolt d. Refined bolts are used for some structural connections that are often disassembled and cannot be riveted. Refined bolts are generally used for mechanical products, and are rarely used in construction steel structures.
2) High-strength bolt connection
Bolts made of high-strength steel or bolts that require a large preload can be called high-strength bolts. High-strength bolts apply pre-tension and transmit external force by friction. Ordinary bolt connection by the bolt rod shear and hole wall pressure to transmit shear, tighten the nut when the pre-tension is very small, the impact can be negligible, while high-strength bolts in addition to its high material strength, but also to the bolt to apply a lot of pre-tension, so that the connection between the members of the squeezing pressure, so that there is a great deal of friction perpendicular to the direction of the screw, and pre-tension, anti-slip coefficient and the type of steel have a direct impact on the high-strength bolts. load-bearing capacity.
High-strength bolts are divided into two main types according to their stress conditions: friction type and pressure type.
High strength bolts are divided into two types according to the construction process: torsional shear type high strength bolts and large hexagonal high strength bolts.
Friction type high-strength bolts are connected by the friction force generated on the contact surface of the steel plate after the tightening pressure of the bolts makes the connection plate layer tight to transfer the external force. The surface of the component is sandblasted to produce a red rust surface, which can obtain a larger friction coefficient and reduce the number of connecting bolts. The aperture of friction type high strength bolts should be 1.5-2.0mm larger than the nominal diameter d of the bolts.
The hole diameter should be 1.0-1.5mm larger than the nominal diameter of the bolt d. The holes are drilled by CNC drilling machine and drilling die.
In short, friction type high-strength bolts and pressure type high-strength bolts are actually the same kind of bolts, the difference lies in whether the design takes into account the slip. Design, friction type high strength bolts friction surface can not slide, the screw does not bear shear, once the friction surface slip, it is considered to reach the design damage state, technically more mature and reliable; pressure type high strength bolts friction surface can slide, the screw also bear shear, the final damage and ordinary bolt damage the same (bolt shear bad or steel plate crush bad).
Large hexagonal high-strength bolts, from a high-strength bolt, a nut and two washers can form a high-strength bolt connection vice.
During construction, the structure is temporarily fixed with rough bolts, and after the structure is installed and corrected, the rough bolts are replaced with high-strength bolts one by one starting from the middle of the bolt group and the initial screwing is carried out, and then the re-screwing and final screwing are carried out in sequence after the initial screwing.
When installing high strength bolts with large hexagonal head, a washer should be added on each side of the bolt. The initial screwing torque value is 50% of the final screwing torque value, the re-screwing torque value is equal to the final screwing torque value, the final screwing torque value calculation formula is: Tc=K*Pc*d. Tc is the final screwing torque value, unit N-m; K is the torque coefficient; Pc is the construction pre-tension, unit kN; d is the high strength bolt thread diameter, unit mm. torque wrench is used for screwing, torque correction should be made before each use.
Torsional shear high-strength bolts, a high-strength bolt, a nut and a washer form a torsional shear high-strength bolt connection
When installing torsion shear high strength bolts, only one washer should be added on the side of the nut. The formula for calculating the initial torque value is: Tc=0.065*Pc*d. Tc is the initial torque value, unit N-m; Pc is the construction pretension, unit kN; d is the diameter of the thread of the high-strength bolt, unit mm. The final screwing is done by using a special wrench to break the end of the plummer head. The focus of quality inspection should be on the supervision and inspection of the construction process.
3) Footing anchor bolts
Footing anchor bolts, alias footing bolts, footing screws, footing wires, etc., are used for the connection of steel structure footing and concrete foundation components. It is generally made of Q235 and Q345 round steel.
Different kinds of footing anchor bolts (diameter greater than 24mm should be used in the form of anchor plate)
The footing anchor bolt group is fixed by the steel frame during installation, installed together with the tied steel cage, and then concrete is poured, and the bolt head should be exposed to the concrete surface for a certain length. After the concrete reaches a certain strength, install the steel column footing, and finally the second grouting at the bottom of the column.
4) Chemical anchor bolts
Chemical anchor bolt is a new type of fastening material, which consists of chemical agent and metal rod body. It is used to install connections of other structures on the completed concrete structure. It can be used in the installation of various steel structures, curtain walls, marble dry hanging construction after the addition of buried parts, but also for equipment installation, highway, bridge guardrail installation, building reinforcement and transformation.
Chemical anchor is a new type of anchor after the expansion anchor, is through the special chemical adhesive, the screw gluing fixed in the concrete substrate drilling, in order to achieve the anchoring of the fixed parts of the composite parts. Because the chemical anchor bolt has a large pullout capacity, it can replace the embedded anchor reinforcement, and is often used in the construction site to forget to install the steel pre-buried parts but the concrete has been poured, with the later addition of the chemical anchor bolt embedded parts to remedy.
The construction steps of chemical anchor bolts are as follows:
- According to the engineering design requirements, drill holes in the base material (e.g. concrete) at corresponding locations. The hole diameter, hole depth and bolt diameter should be determined by professional technicians or field tests.
- Drill the hole with impact drill or water drill.
- Clean up the dust in the drilling with special air cylinder, brush or compressed air machine, it is recommended to repeat no less than 3 times, there should be no dust and open water in the hole.
- Make sure the surface of the bolt is clean, dry and free of oil plaster.
- Make sure the glass tube anchor package is free from any abnormalities such as broken appearance and solidification of chemicals, put the round head facing outward into the anchor hole and push it to the bottom of the hole.
- Use electric drill and special installation jig to insert the screw to the bottom of the hole with strong rotation, and do not use impact method.
- When rotating to the bottom of the hole or the marked position on the bolt, stop rotating immediately and remove the installation jig. Avoid disturbing after the gel until it is completely cured. Overtime rotation leads to loss of glue and affects anchoring force. (Rotation time should not exceed 30 seconds, rotation speed should not be less than 300 rpm and not more than 750 rpm, bolt advance speed is about 2cm/sec, impact is not allowed)
5) Expansion bolts
The role of expansion bolts is the same as the role of chemical anchor bolts, used for anchorages with less force.
No expansion bolts shall be used in the parts of concrete structure with cracks and parts prone to cracks. At the same time, the main load-bearing structures, important pipelines and high-speed operation, impact loading and vibration of the design of the expansion bolts, should be calculated according to the design of the tensile force and the design of the shear force to choose a larger specifications.
The arrangement of bolts and construction requirements
Bolt arrangement is divided into two kinds of parallel and staggered:
- Side by side – simple, neat and compact used to connect the plate size is small, but the member cross-section weakening large;
- Staggered – arrangement is not compact, the size of the connection plate used is large, but the cross-sectional weakening of the member is small.
Force requirements
- Vertical force direction: in order to prevent the bolt stress concentration from affecting each other, the cross-sectional weakening is too much and reduces the bearing capacity, the edge distance and end distance of the bolt cannot be too small;
- With the direction of force action: in order to prevent the plate from being pulled or sheared off, the end distance cannot be too small;
- For compressed members: to prevent bulging of the connecting plates, the middle distance cannot be too large.
Structural requirements
The edge distance and the middle distance of the bolts should not be too large, so as to avoid poor fit between the plates and moisture intrusion and corrosion of the steel.
Construction requirements
- In order to facilitate the tightening of nuts by wrenches, the middle distance of bolts should be not less than 3do;
- According to the above requirements, GB50017-2017 Steel Structure Design Code gives the allowable spacing of bolts and related design values.
Manufacturing process of fasteners
There are different types of fasteners. These include:
- 1. Coil element: Small billets are used as raw material, heated and rolled to make coiled elements, also known as wire or coil.
- 2. Annealing: A metal heat treatment process in which metal is slowly heated to a certain temperature for sufficient time, and then cooled at an appropriate rate (usually slow cooling, sometimes controlled cooling).
- 3. Pickling: A process of cleaning metal surface with acid solution to remove oxide layer and rust on metal surface.
- 4. Phosphating treatment: It is a process of forming phosphide chemical conversion film through chemical and electrochemical reaction. The function of phosphating film is to basically protect the metal, prevent the metal from corrosion, and prevent friction and lubrication at the same time. It belongs to surface treatment. Pretreatment.
- 5. Saponification: refers to the hydrolysis reaction process of oil products catalyzed by alkali. The function of saponification is to further increase the lubrication performance of metal surface, which also belongs to the pretreatment of surface treatment.
- 6. Stretch. The pretreated wire is extruded into the required shape (including appearance and material diameter) with a disc die with appropriate wire diameter.
- 7. Cold heading: a forging method in which a die is used to extrude a metal rod at room temperature. It is usually used to manufacture screws, bolts, rivets and nuts, which can reduce or replace cutting.
- 8. Turning: It is a kind of machining, which mainly uses turning equipment to turn the workpiece blank to obtain the ideal workpiece shape.
- 9. Thread processing (threading, rolling and tapping): Threads are obtained by extruding or cutting the material.
- 10. Heat treatment: the comprehensive process of heating, heat preservation and cooling the material in a certain medium, and controlling its performance by changing the surface or internal structure of the material.
- 11. Surface treatment. It refers to the process of artificially forming a surface layer with different mechanical, physical and chemical properties from the substrate on the surface of basic materials. Its purpose is to meet the requirements of corrosion resistance, wear resistance, decoration or other special functions of the product. We often hear hot-dip galvanizing, blue white zinc plating, bluing, blackening, etc. These are surface treatment processes.
Fastener Coatings and Finishes
Fasteners are available with various coatings and finishes to enhance their performance, appearance, and longevity. Some popular options include:
- Zinc Plating: Offers corrosion resistance and is ideal for indoor applications.
- Galvanized Coating: Provides excellent corrosion protection, making it suitable for outdoor and harsh environments.
- Black Oxide: Improves the appearance and adds a layer of corrosion resistance to fasteners.
- Nickel Plating: Enhances corrosion resistance and provides a decorative finish.
Packing of fasteners
How to Pack Fasteners
Packaging fasteners is a delicate process that requires skill, caution and attention to detail.
It’s important to remember that packaging can be an extra expense for your company, so it’s important to accurately understand your needs. You don’t want to spend money on unnecessary packaging materials or services.
The best way to pack fasteners is to use a vacuum bag system. This method uses heat and pressure to seal the bags around your products to form a custom, airtight seal to protect them from damage during transportation. The bagging system also helps to protect the product from moisture so that it will not rust or corrode during storage.
You can also choose to use shrink wrapping machine to achieve this purpose. This machine seals the plastic on the edge of the product so that it will not be damaged by moisture entering the container during transportation or storage.
Packaging fasteners are a key part of any order fulfillment process. If you don’t know how to pack the fasteners correctly, you may eventually cause damage to the goods or even litigation.
In order to pack the fasteners correctly, you need to use bubble film and air bag to prevent them from shifting during transportation. You should also use packaging peanuts or other cushioning materials, such as paper or foam, to prevent items from rubbing against each other during transportation, which will cause damage over time. It is also important that your packaging materials be clean so that they do not get dirty during storage or transportation.
When you package fasteners in batches, make sure each has its own space so that they will not be damaged during transportation or storage.
Quality inspection of fasteners
How to check fasteners?
The first step in checking fasteners is to identify them properly. There are several different types of fasteners that have different characteristics, so it’s important not to confuse them with each other. After you’ve identified the type of fastener you’re working with, make sure it’s rated for high-quality use by checking its specifications sheet or contacting the manufacturer directly.
If you’re working with a new type of fastener for the first time (or if you want to get more information on how something works), there are plenty of online resources available to help you learn more about them before using them on any project.
When you’re inspecting fasteners, look for the following:
- 1. The heads of screws should be flat and smooth.
- 2. The threads on the bolts should be clean and even throughout their length.
- 3. The ends of all bolts should be smooth and free of burrs or cracks that could cause them to break off in use.
Surface inspection: This is the simplest, most common form of quality inspection. Inspectors will examine a fastener to check for defects, such as pitting or scratches, before it leaves the factory.
Dimensional inspection: This type of quality control involves measuring various dimensions to ensure that they fall within a small tolerance range. For example, if a bolt has been tightened too much during assembly, its diameter will be smaller than expected because it’s compressed from both sides and not just from one side like when you tighten a nut onto a bolt by hand.
Chemical analysis: A machine called an X-ray fluorescence analyzer can detect trace elements present in steel alloys at very low levels—this is useful for detecting impurities like lead or sulfur which would make your fastener less corrosion resistant and more likely to fail prematurely due to stress corrosion cracking (SCC) between two surfaces sharing an electrolyte-containing fluid interface (like salt water). Chemical analysis can also reveal other types of contaminants such as manganese content so we know whether our alloy contains too much manganese which makes it brittle when hardened rather than tough like chrome molybdenum steels should be used instead
Measurement of fasteners
When you’re measuring fasteners, there are a few factors to consider. You’ll need to know the length and diameter of each fastener before you can proceed with anything else. Once you have those numbers, though, it’s time to look at standards.
Many different types of fasteners exist and have been developed over time depending on what they’re being used for and what type of materials they’re going into or coming out of. For instance, if your project requires high-strength bolts that will resist corrosion from salt water exposure then perhaps these three grades would be ideal: Grade 8 (200 ksi), Grade 10 (350 ksi), Grade 12 (500 ksi). The higher the grade number is means greater tensile strength capabilities so these grades would provide much better protection against corrosion than lower grade options such as 5/16th inch flathead lag screws rated for 150 pounds per inch; use this only if no other option were available!
How to improve the quality of fasteners
When it comes to the quality of fasteners, there are many factors that affect the quality of a product.
- Supply chain management
- Process control
- Quality control
- Selection of raw materials
- Technological improvement
- Advanced equipment
- Staff training
- Customer feedback
Cost of fasteners
The cost of fasteners depends on the raw material and the labor cost. The exchange rate between USD and RMB affects the cost of fasteners.
How to Choose Industrial Fasteners
What should you be looking for in a fastener? Here are a few things to consider.
- 1. Strength.
- 2. Brittleness.
- 3. Corrosion resistance.
- 4. Electrical coupling corrosion performance.
- 5. Cost.
When selecting fasteners for industrial applications, a variety of factors and characteristics must be considered, including:
- The type of thread.
- The applied load on the fastener.
- The stiffness of the fastener.
- The number of fasteners required.
- Accessibility.
- Environmental factors (meaning temperature, water exposure and potential corrosion factors).
- Installation process.
- Material to be connected.
- Reusability.
- Weight limitations.
Fasteners can sometimes be supplied with coatings (e.g. cadmium plated, zinc plated, phosphate plated) to improve their corrosion resistance and general performance.
How to find reliable fastener manufacturers
To get the best fastener manufacturers, you’ll want to find out:
- The reliability of each manufacturer. To do this, ask for a certificate of quality and check the manufacturer’s website for information about its certification. You can find information on third-party inspections and payment terms there as well.
- The delivery time and after-sales service offered by each manufacturer.
- Whether or not a particular manufacturer offers warranty on its products or services (and what kind of warranty it is).
Place an order of fastener
- You can contact us by email or phone.
- You can also visit our factory.
- You need to tell us the size and quantity of fasteners you need.
- We will send you the quotation.
- You need to pay a deposit.
Source: China Fasteners Supplier: 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.)
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