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Construction process standards for copper and brass piping

This process standard applies to the installation of purple copper piping with a working pressure of 4MPa or less and a temperature of 250-196℃ and brass piping with a working pressure of 22MPa or less and a temperature of 120-158℃.

20211012114335 70388 - Construction process standards for copper and brass piping

Construction preparation

Commonly used materials

Tubes: Commonly used are purple copper pipes (industrial pure copper) and brass pipes (copper-zinc alloy) are divided into control pipes, rolled pipes and extruded pipes according to the different manufacturing methods, and generally drawn pipes are used for medium and low pressure pipes. Commonly used material grades for copper tubes are: T2, T3, T4, TUP (deoxidized copper); divided into two types of soft and hard. Brass tube commonly used material grades: H62, H68, H85, HP659-1, divided into soft, semi-hard and hard three.

Brass alloy

In order to improve the performance of brass, add tin, manganese, lead, zinc, phosphorus and other elements in the alloy to become special brass. The role of the added elements is briefly described as follows.
Adding tin can improve the strength of brass, and can significantly improve its corrosion resistance to seawater, so tin brass is also known as “naval brass”.
Adding manganese can significantly improve the alloy process performance, strength and corrosion resistance.
The addition of lead improves the cutting performance and corrosion resistance, but slightly reduces plasticity.
Adding zinc can improve the mechanical properties and fluidity of the alloy.
Adding phosphorus can improve the toughness, hardness, wear resistance and fluidity of the alloy.

Applications of copper tube

Most of the copper and brass tubes used in the manufacture of heat transfer equipment; also commonly used in deep cooling devices and chemical pipelines, instrumentation pressure measurement lines or transmission of pressurized liquid pipelines are often used. When the temperature is greater than 250 ℃, should not be used under pressure.
Extruded aluminum bronze tubes made of QAI10-3-1,5 and QAI10-4-4 grades of bronze, used in machinery and aviation industry, manufacturing wear-resistant, corrosion-resistant and high-strength pipe fittings.
Tin bronze tubes are made of QSn4-0.3 and other grades of tin bronze, which are suitable for manufacturing spring tubes and wear-resistant fittings for pressure gauges.

Quality of copper pipe

For the installation of copper tubes and copper alloy tubes, the surface and inner wall should be clean, no defects, cracks, scars, tail cracks or pores. Brass pipe should not have green rust and serious dezincification.
The outer surface defects of copper and copper alloy carriages are allowed as follows.
Longitudinal scratches depth as shown in Table.1; partial lateral recess depth or projection height is not more than 0.35mm; scar bruises, blisters and pits, the depth of which does not exceed 0.03mm, and its area does not exceed 30% of the surface area of the tube. When used as a conduit, the area does not exceed 0.5% of the surface area of the tube.

Table.1 Copper and copper alloy tube longitudinal scratch depth regulations

Wall thickness(mm

Longitudinal scratch depth not greater than(mm

Wall thicknessmm

Longitudinal scratch depth not greater than(mm





Note: Copper and copper alloy pipes used for conduit, regardless of wall thickness, the depth of longitudinal scratches should not be greater than 0.03mm.
The ellipticity of the copper pipe and the unevenness of the wall thickness should not exceed the permissible deviation of the outer circle and wall thickness.
Other technical requirements of the copper tube shall comply with the following standards.

  • 1. “Control copper pipe” (GB1527-79).
  • 2. “Extruded Copper” (GB1528-79).
  • 3. “Drawn Copper” (GB1529-79)
  • 4. “Extruded Copper” (GB1530-79).

Copper and copper alloy pipe fittings

Copper and copper alloy fittings are not yet common national standard fittings, elbows, tees, reducers, etc. are made with pipe processing.

Commonly used copper and copper alloy welding rod

Commonly used copper and copper alloy welding electrode grades and uses Table 2. copper and copper alloy welding electrodes are low-hydrogen flux; welding power are DC.
Table.2 Copper and copper alloy electrode grades and uses

Welding rod brand Equivalent to international model Material of welding core Weld metal Main purpose
Main components% Tensile strength% Elongation%
T107 TCu Pure copper Copper > 99 ≥1770 Cold change angle ≥ 120 ° Welded copper parts can also be used for surfacing carbon steel parts resistant to seawater corrosion.
T227 TcuSnB Tin Phosphorus Bronze Tin ≈ 8, phosphorus ≤ 0.3, copper allowance ≥2750 ≥20 Welding tin phosphorus bronze, copper, brass, cast iron and steel parts; It is widely used in soldering tin phosphor copper bushing, ship propeller sheet, etc.
T237 TcuAl Aluminum bronze Aluminum ≈ 3, manganese ≤ 2, copper allowance ≥3920 ≥15 Welding aluminum bronze and other copper alloys, welding of copper alloy and steel, repair welding of iron castings, etc.

Copper and copper alloy welding wire

Used for oxy-acetylene welding, argon arc welding, carbon arc welding copper and copper alloys, where brass wire is also widely used for brazing carbon steel, cast iron and carbide tools, etc.. When welding, it should be used with copper gas welding solvent.
20211012113450 42329 - Construction process standards for copper and brass piping

Table.3 Copper and copper alloy welding wire main components, properties and applications

Welding wire grade

Equivalent ministry standard model

Welding wire name

Main components of welding wire(%

Tensile strength of welded joint

Melting point of welding wire


Base metal




Special red copper welding wire

Tin 1.1, silicon 0.4, manganese 0.4, copper surplus

Red copper





Low phosphorus copper welding wire

Phosphorus 03, copper surplus

Red copper





Tin brass welding wire

Copper 60, tin 1, silicon 0.3, zinc balance






Iron brass welding wire

Copper 58, tin 0.9, silicon 0.1, iron 0.8, zinc allowance






Silicon brass welding wire

Copper 62, silicon 0.5,

Zinc surplus




Welding wire grade

Performance and Application


Excellent welding process performance, good weld formation, high mechanical properties and good crack resistance. It is suitable for sub arc welding and oxygen acetylene gas welding of red copper (pure copper)


The fluidity is better than that of ordinary red copper. It is suitable for oxyacetylene gas welding and sub arc welding of red copper


It has good fluidity and mechanical properties. It is suitable for oxygen acetylene gas welding brass and brazing copper, copper nickel alloy, gray cast iron and steel. It is also used for inlaying cemented carbide tools


The smoke is small during welding, and other properties and uses are the same as those of “HS221”


It can effectively eliminate air holes and has good mechanical properties. Its purpose is the same as “HS221”

Note: Welding wire size (mm): circle one diameter 1.2; strip one diameter 3, 4, 5, 6; length 1000.

Solvent for gas welding

Role of flux

  • a. And oxygen in the metal, sulfide combined, so that the metal reduction.
  • b. Replenish favorable elements and play an alloying role.
  • c. Form slag and cover the surface of the molten metal pool to prevent continued oxidation of the metal.
  • d. Play a protective role, so that the weld slowly cooled, improve the crystalline organization of the joint.

Applicable fluxes for copper and copper alloys

  • a. CJ301 copper gas welding flux. Performance: melting point of about 650 ℃, acidic reaction, can effectively melt copper oxide and cuprous oxide; welding generates liquid slag to cover the surface of the weld to prevent metal oxidation. Use: Flux for gas welding copper and copper alloy parts.
  • b. Flux composition is shown in Table
  • c. Self-made oxygen welding flux see Table

Copper alloy gate valve, globe valve and check valve structure length see GB12221-86.
Copper and copper alloy pipeline used valves, flanges and gaskets, should be selected according to the nature of the transported media, temperature, pressure.
Table.3 Commonly used copper welding and copper alloy welding flux table

Boric acid H3BO3

Borax Na2B4O7

Sodium hydrogen phosphate Na2HPO4

Potassium carbonate K2CO3

Sodium chloride NaCl













Table.4 Self-made oxygen welding flux composition table

Flux code

Flux composition(%

Scope of application


Boric acid 50, borax 50

Gas welding copper and copper alloy


Borax 35, anhydrous fluorination 42 ± 2

Welding copper alloy pipe with silver solder


Boric acid 75, borax 25

Welding or brazing of copper and copper alloy pipes


Boric acid 50, anhydrous potassium fluoride 50

Brazing bronze and beryllium bronze with silver


Sodium oxide 20, sodium chloride 12 ~ 16, barium chloride 20, potassium chloride residue

Welded tin bronze

Commonly used machines

Machine tools: abrasive wheel saw, hand drill, table drill, impact drill, DC welding machine, argon arc welding machine, etc.
Tools: live wrench, wrench, hand hammer, burin, scribing needle, bench vise, hand saw, pipe bender, edge wrench, manual test pump, rubber hammer, straightener, file, oxygen cylinder, acetylene cylinder, oxygen meter, pressure meter, acetylene meter, gas welding gun, cutting gun, welding wire, welding pliers, wire cutters, awl, hammer.
Measurements: steel tape measure, steel plate ruler, level ruler, flange angle ruler, welding inspection ruler, measuring angle gauge, oil caliper, line drop, level meter, latitude and longitude meter.

Working conditions

The construction of civil engineering related to the pipeline is completed and has been accepted, and the copper pipe installation can be ensured continuously.
The equipment connected with the pipeline has been leveled, squared and fixed, and the secondary grouting has been completed.
The required drawings, information and technical documents have been prepared, and the drawings have been reviewed and the design has been submitted.
The construction plan has been prepared and the construction personnel have issued the “engineering task order” and “limit material order”. The necessary technical training has been completed.
Pipes, valves and piping accessories have been checked according to the design requirements, with certificates of conformity and relevant information. Cleaning and degreasing work has been completed.
The preparation work such as machinery and tools proposed in the construction plan or technical measures has been completed.
Using expansion or flanging connection of the pipe, before construction should be 1% of each batch and not less than two for expansion or flanging test. If there are cracks need to anneal and redo the test. If there are still cracks, there is the batch of pipes need to anneal and test one by one, and those who do not pass shall not be used.
Materials, labor and machinery are basically complete; the construction site meets the requirements; construction water, electricity, roads, etc. can meet the needs and can ensure continuous construction as planned.

Operation process

Process flow

Copper pipe straightening → cutting → bending → threaded connectionflange connection → welding → tungsten argon arc welding → preheating and heat treatment → bracket and pipe through the wall installation → compensator installation → valve installationhigh pressure pipe installation → degreasing → pressure test → pipe oil cleaning

Copper pipe straightening

Copper and copper alloy pipeline straightening should be filled with sand first, and then straightened with a straightener; sand-filled copper pipe can also be placed on a flat plate or workbench and placed on it with a wooden mat, and then rubber hammer, wooden flogger or square wood along the body of the pipe gently knocked and straightened section by section.
Be careful not to use too much force in the straightening process, and not to make hammer marks, pits, scratches or rough traces on the surface of the pipe. Design logistics should be cleaned up the residual sand in the tube, etc.


Copper and copper alloy tube cutting can be used hacksaw, wheel saw, but shall not use oxygen – acetylene flame cutting.
Copper and copper alloy tube bevel processing using files or beveling machine, but shall not use oxygen – acetylene flame to cut processing. Clamping copper pipe on the table under the vise mouth on both sides should be padded with a wooden board liner to prevent pinching the tube


Copper and copper alloy tube simmering bend as far as possible without hot simmer, because after the hot simmering tube filler (such as river sand, rosin, etc.) is not easy to remove. General pipe diameter of 100mm below the use of cold bending, bending machine and operating methods and stainless steel cold bending base the same. Pipe diameter of 100mm or more using pressed elbow or welded elbow.
The length of the straight edge of the copper bend should not be less than the diameter of the pipe, and not less than 30mm.
Bend processing should also be based on the material, pipe diameter and design requirements and other conditions to decide.

Hot simmer bend

First filled with dry fine sand without impurities, and wooden hammer knocked solid, and then blocked with wooden plugs at both ends of the mouth, and then painted on the wall of the pipe heating length of the mark, should make the straight edge of the bend length is not less than its diameter, and not less than 30mm.
Heating the heating section of the pipe body with wood charcoal; such as the use of charcoal collection heating, should be carried out under the conditions of closing the charcoal stove blowers, and constantly rotate the pipe to make heating uniform.
When heated to 400 ~ 500 ℃, quickly remove the tube on the tire tool bending, in the bending process shall not pour water on the tube body cooling.
Hot simmering bend, the tube is not easy to remove the river sand available concentration of 15% ~ 20% of hydrofluoric acid in the tube stored for 3 hours to make it dissolved, and then 10% ~ 15% of the alkali neutralization, with clean hot water fall out of the flush, and then in 120% ~ 150% temperature by 3 ~ 4 hours drying.

Cold simmering bending

Cold simmer bending is generally used for purple copper pipe. Operation process of the first two channels with this article a 1 and 2. Subsequently, when heated to 540 ℃, immediately remove the tube, and its heating part of the water, wait for it to cool, and then put on the tire tool bending.

Threaded connection

The thread of the threaded connection must have an outside diameter comparable to the standard thread of the welded steel pipe in order to obtain a complete standard thread. However, the threads used for high pressure copper pipes must be machined on a lathe and constructed according to the requirements of high pressure pipes. When connecting, its threaded part must be coated with stone and glycerin as sealing filler.

Flange connection

The flanges used on copper and copper alloy piping can be connected with different forms of flanges according to the different pressures they are subjected to. Flange connection is generally in the form of flanged flange, flat welding flange and butt welding flange, etc., the specific selection should be in accordance with the design requirements. General pipeline pressure within 2.5MPa using smooth surface cast copper flange connection; when the pressure is within 6.4MPa using concave and convex surface cast steel flange connection. Flange and bolt material grades should be selected according to the relevant standards promulgated by the state. Nominal pressure in 0.25MPa and 6MPa pipeline connection, the use of copper sleeve flanged flange or copper pipe flanged flanged flange.
Copper flanges connected with copper pipes and copper alloy pipes should be welded, and the welding method and quality requirements should be consistent with the welding of steel pipes.
When the design does not specify, the gasket in the flange connection of copper and copper alloy pipes can generally use rubber asbestos gasket or copper gasket.
The cylindrical surface of the outer edge of the flange should be marked with the material grade, nominal pressure and nominal diameter. For example, if the flange material grade is H62, PN=2.5MPa, DN=100mm, the stamp mark is: H6225-100.

Lap joint flange

When the pipe is connected with a live sleeve flange, there are two structures: one is the pipe flange (Figure, and the other is the pipe welded weld ring. The weld ring is made of the same material as the pipe. Flanged live sleeve flange and welding ring size specifications are detailed in the Ministry of Chemical Industry and the former Ministry of a machine flange standards.

20211012121436 74865 - Construction process standards for copper and brass piping

Barrel tube stub end

20211012121446 27450 - Construction process standards for copper and brass piping

Mold of stub end
(a) Inner mold; (b) Outer mold

Copper and copper alloy tube stub end die has inner die and outer die.

The inner die is a conical steel die, whose outer diameter should be equal to or slightly smaller than the inner diameter of the flanged pipe. The outer die is a two-piece long-necked half flange as shown in Figure.5.
In order to eliminate the internal stress of the flanged part of the material, before the tube is flanged, measure out the flanged width of the tube end as shown in Table.5, and then draw a line. Heat this length with a gas welding nozzle to above the recrystallization temperature, usually about 450°C. Then cool naturally or pour water to cool sharply. After the tube end cools, set the inner and outer die on and fix it on the table, and tap the flap with a hand hammer or use a press. After all the flip and then knock flat file, that is to complete the flip operation.
Table.5 Copper tube flanging width (mm)

Nominal diameter DN














Width of stub end







The steel pipe flanging connection shall keep the two pipes coaxial with the deviation of ≯ 1mm for nominal diameter ≤ 50mm and ≯ 2mm for nominal diameter > 50mm.
The sealing gaskets between copper flanges are generally made of asbestos rubber sheets or copper gaskets, but other materials can be selected according to the temperature and pressure of the conveyed medium.


Copper in the welding process, there are easy to oxidation, easy to deformation, easy to evaporation (such as zinc, etc.), easy to generate porosity and other undesirable phenomena, to welding difficulties. Therefore, when welding copper pipes, you must reasonably choose the welding process, the correct use of welding tools and welding parts, strict compliance with the welding procedures, and constantly improve the operating techniques in order to obtain a high-quality weld.
When the design is not clearly specified, the welding of copper pipelines should be manual tungsten arc welding; copper alloy pipelines should be used for oxy-acetylene welding.
To prevent the flow of molten liquid into the pipe, the following forms of welding are appropriate.
Pipe diameter of 22mm or less, the use of manual expansion machine to expand the mouth into a socket insert welding, or the use of casing welding (casing length L = 2 ~ 2.5D, D for the pipe diameter). But the expansion length of the socket should not be less than the pipe diameter, and should be installed in the direction of media flow as shown.
20211012122345 12145 - Construction process standards for copper and brass piping
Copper and copper alloy pipe socket welding and casing welding
The same caliber copper pipe butt welding, can be used to add the welding ring lining method of welding.
Bevel type: When the design does not specify, butt welding should comply with the provisions of Table.6.
Table.7 Copper and copper alloy pipe, pipe fittings bevel type, size and group clearance (mm)

Welding technology Serial number Groove name Groove form Size Remarks
Wall thicknesss Clearance c Blunt edge p Groove angle d
Argon tungsten arc welding of red copper 1 I type 20211012122851 39530 - Construction process standards for copper and brass piping 2 0
2 V type 20211012122901 10844 - Construction process standards for copper and brass piping 34 0 65°±5°
3 V type 20211012122921 20087 - Construction process standards for copper and brass piping 58 0 12 65°±5°
Brass oxyacetylene welding 1 I type 20211012122931 57073 - Construction process standards for copper and brass piping ≤3 Single side welding
20211012122941 92484 - Construction process standards for copper and brass piping 36 35 Double sided welding shall not be carried out at both sides at the same time
2 V type 20211012123009 60975 - Construction process standards for copper and brass piping 812 36 0 65°±5°
3 V type 20211012123019 16870 - Construction process standards for copper and brass piping 6 36 3 65°±5°

Grouping: should reach the inner wall ridge flat, the amount of the wrong side of the inner wall shall not exceed 10% of the wall thickness of the pipe, and not more than 1mm. different wall thickness of the pipe, pipe fittings grouping can be in accordance with the carbon steel pipe phase respect such as bin should provide for the processing of pipe bevels.

Bevel cleaning: bevel surface and its edges inside and outside not less than 20mm range of the surface, should be used before welding with motor vehicle solvent to remove oil, using mechanical methods or chemical cleaning to remove the oxide film, so that it reveals the metal luster. Solder wire before use should also apply the same method of self-care.
Copper and copper alloy pickling operating conditions are shown in Table.7.
Table.7 copper and copper alloy pickling operating conditions


Composition of solvent



Sulfuric acid 10%, water 90%



Phosphoric acid 4%, silicon with sodium 0.5%, water 99.5%



Note: Formulation I in the table is not applicable to the treatment of bronze and aluminum bronze.
Copper and copper alloy materials treated by the formula listed in Table.7 must be rinsed with water, then rinsed with hot water and preferably passivated.
The composition and operating conditions of the passivation solution are shown in Table 8.
Table.8 Composition and operating conditions of passivation solution

Composition of passivation solution

Operating temperature(℃)


30ml sulfuric acid, 90g sodium chromate, 1g sodium chloride and 1L water



Note: The passivated workpiece should be rinsed with cold water first, followed by hot water and dried.

Gas welding

The diameter of the welding wire is approximately equal to the thickness of the wall, can use general purple copper wire or “HS201” (special purple copper wire), “SH202” (low phosphorus copper wire); gas welding flux can be used “CJ301 “. Before welding, clean the end of the tube and wire, and sandpaper carefully polished, so that the end of the tube is not too hairy, and not too light.

Manual arc welding

a. Copper conductivity, preheat before welding (with oxygen – acetylene preheat to 200 ℃ or more), and weld with a higher current.
b. Copper coefficient of linear expansion (about 50% greater than mild steel), rapid thermal conductivity (about 8 times greater than mild steel), large heat-affected zone, greater shrinkage stress during solidification, so the assembly gap should be larger.
c. According to the pipe composition and wall thickness and other factors, to the correct choice of welding rod type, diameter and welding current intensity. See Table 1-68 and Table.9.
Table.9 Welding current reference table

Welding of butt welded joints

Welding of lap joints

Thickness of pipe wall(mm

Diameter of electrode(mm

Intensity of current(A

Thickness of pipe wall(mm

Diameter of electrode(mm

Intensity of current(A































d. When welding brass, in order to reduce evaporation and oxidation at high temperatures, the welding current intensity should be smaller than that of purple copper. As zinc evaporation is easy to make people poisoning, should be selected in the air circulation place welding.
e. Copper in welding should be used when the DC power supply reverse polarity connection (workpiece connected to the negative pole).
f. After welding, while the weld is in the hot state, tap the weld with a small flat hammer to eliminate thermal stress, make the metal organization dense and improve mechanical properties.
Brazing: brazing strength is small. The general welding mouth is in the form of a lap joint. The lap length is 6 to 8 times the thickness of the pipe wall. When the nominal diameter of the tube (D) is less than 25mm, the lap length is (1.2 to 1.5) D (mm).
After brazing, the tubing must be cleaned within 8 hours to remove the residual flux and slag. Commonly boiled alum solution containing 10%-15% is used to brush the joint, and then rinsed and dried with water.

Tungsten Argon Arc Welding

The tungsten electrode is used instead of the carbon electrode in carbon arc welding, and the molten pool is protected with argon (inert gas) to obtain a high-quality welded joint.
Use of welding wire: When tig welding of purple copper, use a wire containing deoxidized non-element, such as HS201, HS202; if you use a wire without deoxidized element, such as T2 grade, you need to use it at the same time with copper welding flux CJ301.
Spot welding positioning: the length of the spot-fixing weld should be thin and long (20-30mm), and if cracks are found should be shoveled off and rewelded.
Copper tungsten arc welding using DC positive polarity left welding method.
Operation, the arc length is maintained at 3 ~ 5 mm, 8 ~ 14 mm. to ensure the quality of the weld fusion, often using preheating, high current and high speed for welding. Wall thickness of less than 3mm, preheating temperature of 150 ~ 300 ℃; wall thickness greater than 3mm, preheating temperature of 350 ~ 500 ℃; width to the center of the weld mouth as a reference, not less than 100mm on each side. preheating temperature should not be too high, otherwise the heat-affected zone is expanded, and poor labor conditions.
Copper tungsten arc welding parameters such as Table.10.
Table.10 Copper tungsten electrode manual argon arc welding parameters

Plate thickness(mm

Tungsten electrode diameter(mm

Diameter of welding wire(mm

Welding current(A

Argon flowL/min

Nozzle diameter(mm































Welding should pay attention to prevent the phenomenon of “tungsten trapping” and Yong-end cracking. Can be used to lead the plate or the beginning of the end of the welding section, a short pause, cool a cool then welding.

Preheating and heat treatment

In addition to the requirements mentioned in the above articles.
Brass welding, its preheating temperature: wall thickness of 5 ~ 15mm, 400 ~ 500 ℃; wall thickness greater than 15mm, 550 ℃.
Brass oxy-acetylene welding, preheating width to the center of the weld mouth as a reference, each side of 150mm.
Brass welding, the weld should be post-weld heat treatment. Post-weld heat treatment temperature: stress relief treatment for 400 ~ 450 ℃; softening annealing treatment for 550 ~ 600 ℃. Pipe welding heat treatment, generally should be carried out in a timely manner after welding.

Bracket and pipe through the wall

Bracket installation should be flat and firm, the spacing and specifications should be in line with the specifications and design requirements. Pipeline through the wall and floor should be added steel casing, casing filled with mace.

Compensator installation

When installing copper waveform compensator, its straight pipe length shall not be less than 100mm, other technical requirements in accordance with the requirements of the relevant chapter.

Installation of valves

Before installation, check carefully to verify the model and specification, whether it meets the design requirements. Check whether the valve stem and valve disc is flexible, there is no jamming and skewed phenomenon valve disc must be closed tightly.
Before installation, the valve must first strength and tightness test, unqualified shall not be installed. Valve test provisions are as follows.
Low-voltage valves should be from each batch (with the manufacturer, the same specifications, the same model, while arriving) in a sample of 10%, at least one, for strength and tightness test. If there are unqualified, and then a sample of 20%, if there are still unqualified need to check one by one.
High and medium pressure valves and conveying toxic (toxic, highly toxic substances, see the provisions of the State Administration of Labor issued by the “Pressure Vessel Safety Supervision Regulations”) and A, B fire substances (see “Fire Design Code”) valves should be tested individually for strength and tightness.
Valve strength and tightness test should be clean water, when the working medium for light petroleum products or temperature greater than 120 ℃ of petroleum distillation products of the valve, the application of kerosene for testing.
Valve strength and tightness test should be carried out in accordance with the following provisions.

  • a. Nominal pressure is less than or equal to 32MPa valve whose test pressure is 1.5 times the nominal pressure.
  • b. Nominal pressure greater than or equal to 32MPa of the valve whose test pressure according to Table.11.

Table.11 greater than 32MPa valve strength test pressure

Nominal pressure(MPa






Test pressure(MPa






c. The test time is less than 5 minutes, the shell, packing no leakage for qualified.
In addition to butterfly valves, check valves, bottom valves, throttle valves, tightness test should generally be nominal pressure, in the case of not being able to determine the nominal pressure, also available 1.25 times the working pressure test to the valve sealing surface does not leak for qualified. Nominal pressure is less than or equal to 2.5MPa water supply with cast iron, cast bronze gate valve is allowed to have no more than the amount of leakage Table.12.
Table.12 Gate valve sealing surface leakage allowed

Nominal diameter(mm) Leakage(cm3/min) Nominal diameter(mm) Leakage(cm3/min) Nominal diameter(mm) Leakage(cm3/min)
≤40 0.05 350 2 900 25
50-80 0.1 400 3 1000 30
100-150 0.2 500 5 1200 50
200 0.3 600 10 1400 75
250 0.5 700 15 ≥1600 100
300 1.5 800 20

Nominal pressure is less than 1MPa, and the nominal diameter of the gate valve greater than or equal to 600mm may not unit for hydraulic strength and tightness test. Strength test in the system test pressure according to the test pressure of the pipeline system, tightness test available color printing method for the gate sealing surface inspection, according to the surface should be continuous.

The tightness test of the welded valve is carried out separately, and the strength test can generally be carried out during the system test.
Tightness test failed valve, shall be disassembled to check and re-test.
Alloy steel valves should be spectral analysis of the shell one by one to review the material. Alloy steel and high-pressure valves take 10% of each batch, and not less than one, disassembly to check the internal parts of the valve, such as unqualified need to check one by one.
Disassembly check the quality of the valve should meet the following requirements.

  • a. Internal parts of alloy steel valves for spectral analysis, the correct material.
  • b. The valve seat is firmly bonded to the valve body.
  • c. The combination of the spool and the valve seat is good and free of defects.
  • d. The connection between the valve stem and the spool is flexible and reliable.
  • e. Stem without bending, rust, stem and packing gland fit properly, no defects in the thread.

Test qualified valves, the internal water should be drained in a timely manner, the sealing surface should be coated with antirust oil (except for degreased valves), close the valve, close the entrance and exit. High-pressure valves should fill out the “high-pressure valve test records” (Table.13)
Table.13 high pressure valve test records
Name of the unit project: _ Name of the component project:_  Manufacturer’s certificate number:_  Year Month Day

Valve No




Nominal pressure(MPa

Test pressure




















































































Department head:                          Quality inspector:                           Testers:

Horizontal pipeline on the valve, the valve stem should be vertical or to the left and right 45 °, can also be installed horizontally, but not down; vertical pipeline on the valve stem, must be installed in the direction of the operating circuit.
Valve installation should be kept closed, and pay attention to the characteristics of the valve and media flow direction.
When the valve is connected to the pipeline, the connection bolts on the flange shall not be forcibly tightened; for the threaded connection of the valve, its threads should be intact, tightening is appropriate to use a wrench to jam the hexagonal body at one end of the valve.
When installing a threaded valve, a live joint should generally be added at the outlet of the valve.
For the valve with operating mechanism and transmission device, the operating mechanism and transmission device should be installed after the valve is installed, and they should be cleaned before installation, and they should be adjusted flexibly and indicated accurately after installation.
The inner cavity of the valve body of the stop valve is asymmetrical on the left and right sides, and attention must be paid to the direction of fluid flow during installation. The fluid in the pipeline should be made to flow from the bottom up through the valve disc, because the fluid resistance of such flow is small, open with less effort, and the packing is not in contact with the medium after closing, which is easy to overhaul.
Gate valve should not be installed upside down. When installed upside down, so that the medium is stored in the valve body lifting space for a long time, maintenance is also not convenient. Gate lifting, the rope should be bolted to the flange, do not bolt on the hand wheel or valve parts to prevent breaking the stem. Open stem valve can not be installed in the ground, to prevent the stem rust.
Check valve has a strict directional, installation in addition to attention to the valve body marked media flow direction, but also must pay attention to the following points.
Installation of lift check valve should be installed horizontally, to ensure that the valve disc lift flexible and reliable work.
Rocker plate check valve installation, should pay attention to the flow direction of the medium, as long as the rocker plate rotation pivot is horizontal, can be half in the horizontal or vertical pipeline.
Installation of safety valves must comply with the following provisions.

  • Lever safety valve to have a device to prevent the weight from moving on its own and to limit the lever out of the hand frame.
  • Spring-loaded safety valves to have a lifting handle and a device to prevent random unscrewing of the adjustment screw.
  • Static weight type safety valve to have a device to prevent the heavy piece from flying off.
  • Impulse type safety valve impulse access conduit on the valve, to keep fully open and sealed.
  • Check its verticality, when found tilted, should be in the correction.
  • Tuning conditions of different safety valves, in the pipeline into trial operation, should be timely tuning.
  • The final adjustment of the safety valve is appropriate on the system, the opening pressure and return to the seat pressure should Be in accordance with the design documents.
  • The safety valve adjustment, there shall be no leakage under the working pressure.
  • After the final adjustment of the safety valve qualified, re-seal, and fill out the “safety valve adjustment test records.

High-pressure pipeline installation

The pipe material should be marked out. After the high-pressure pipes supplied in bundles are disassembled, each pipe should be promptly marked with paint or stamped with steel to identify its material. During the installation process, when the paint mark or steel mark on the high pressure pipe is worn away or cut off, it should be immediately repainted with the mark or steel mark. High pressure pipe fittings, fasteners, valves and their accessories used must be strictly classified and stacked according to their materials, temperature levels, product numbers, etc., and are separately marked with a sign indicating that they are strictly prohibited to be used in error.
Connection form. High-pressure pipe connection forms are welding, flange connection and threaded connection, but must be connected in strict accordance with the design requirements of the connection form, not arbitrarily changed.
Pipe inspection before use.
High-pressure pipes should be cleaned up internally before installation and checked with white cloth to achieve no rust, spoil, water, etc. before use.
The threaded part should be cleaned, inspected for appearance, without defects, and coated with molybdenum disulfide (except for those with degreasing requirements).
Seal surface and gasket finish should meet the requirements, no scratches, spots and other defects affecting the sealing performance, and coated with machine oil or white petroleum jelly (except for those with degreasing requirements).
The welding of high pressure steel pipeline must be in strict accordance with the design and specification requirements. The welding rod and wire used should have the factory certificate of conformity, and should be baked according to the requirements of the product specification before use; the welder’s examination and welding methods and welding materials, must be consistent with the actual project execution.
High-pressure pipeline welding as far as possible using the rotation of flat welding.
Requirement to use argon arc welding priming high-pressure pipeline, priming should be filled with argon gas protection inside the pipe, and timely completion of filling and cover welding.
High-pressure pipeline bevel type, size and group gap of welding should generally be made according to the design requirements.
Grouping requirements.

  • a. When the wall thickness ≤ 15mm, the wrong side ≤ 0.5mm.
  • b. Wall thickness > 15mm, the wrong side of ≤ 1mm.
  • c. After jointing, the axis of the two orifices should be in the same line, and the skew error ≤ 1‰.

Before welding, the bevel and a total of 10-20mm wide nearby surface should be cleared of dirt, oil, water and rust. Welding, spot welding should be ground off the welding flesh, and then weld. Welding rod, wire quality, chemical composition and mechanical properties and welding rod diameter and welding layer must be strictly in accordance with the design and the provisions of the relevant specifications.
The allowable minimum ambient temperature of welding, preheating requirements, post-weld heat treatment, pickling, passivation treatment, weld appearance inspection, radiographic and ultrasonic flaw detection, etc., should be carried out in accordance with the design and relevant specifications.
When welding, both ends of the pipe should be blocked to prevent ventilation inside the pipe; at the same time, welding should not be carried out in places with penetrating wind or in rain or snow.
Each weld should be welded at one time, shall not be interrupted, such as having to interrupt, should take measures to make it slowly cool; continue welding again, must be cleaned first, should be in the original arc break 6 ~ 10mm to start the arc. If you need to preheat, must be reheated.
After welding the high-pressure pipe, it must be inspected according to special regulations.

Flange connection

The threaded part, sealing surface and sealing gasket shall be cleaned before installation. Then carry out an appearance inspection to make sure there are no defects affecting the sealing performance. The processing size of the threaded flange shall conform to H12-67, and the flange end face and thread centerline shall be perpendicular to each other, and when the nominal diameter is ≤50mm, the deviation of non-perpendicularity shall be <1mm; when the nominal diameter is >50mm, the deviation of non-perpendicularity shall be <1.5mm.
The threaded part shall be coated with molybdenum sulfide, and the sealing surface and gasket shall be coated with machine oil or white petroleum jelly, except for the design requirement of degreasing.
Screw the threaded flange onto the pipe end threads with the chamfer of the pipe end threads exposed, and place the metal gasket accurately into the sealing seat of the threaded flange.
Insert the double-headed bolts into the screw holes of each group of flanges, and then bring all the nuts on both ends and hand-tighten each nut until it does not move.
Use the torque wrench to further tighten each nut in the order of symmetrical cross shape, the force should be uniform and consistent, and it is appropriate to finish in two to three times. The exposed length of both ends of the tightened bolt should be the same, and not less than two buckles of threads, and the flange and metal gasket should be concentric.
Butt-welding flange connection: The welding process of flange and pipe is consistent with the welding process of this pipe. The flange to flange connection method is consistent with the high pressure threaded flange connection.

Threaded connection

Threaded connections are generally only used for high-pressure pipelines with a nominal diameter <20mm that can be disassembled and connected.
The basic size and processing length of high pressure pipe threads using threaded connection should be in accordance with the design requirements or construction specifications. The formation and size of the sealing surface of the pipe shall conform to the design requirements or the relevant national standards and standards promulgated by the Ministry.
High pressure pipe threads and sealing surface must be machined by lathe. When turning high pressure pipe threads, the inner circle shall be centered and the pipe shall not be subjected to excessive force in the fixture.
The machined pipe threads shall be inspected with a thread gauge; a single match inspection can also be performed with a qualified threaded flange, i.e., no loosening when screwed in with bare hands. The thread roughness meets the requirements, and the surface shall not have cracks, dents, burrs and other defects. The thread with slight mechanical damage or incomplete section should be no more than 1/3 turn in total length. The reduction of thread height shall be no more than 1/3 of its height.
For the machined tapered sealing surface of the pipe, a sample plate must be used for light transmission inspection. After turning the first sealing surface of each specification, the standard lens pad shall be used for color printing inspection, and its contact line shall not be interrupted or deviated. Pipe end tapered sealing surface shall not have scratches, scratches, dents, gnawing knife and other defects, roughness should not be less than the standard requirements Ra3.2, angular error should not be greater than ± 5 °. The sealing surface of the tube end of the flat gasket seal shall be perpendicular to the centerline of the tube, and the roughness shall not be less than the specified requirements.
The used high-pressure female pipe joint must match the product certificate of conformity in specification, model and marking. The appearance should be checked piece by piece before use, and there should be no defects affecting the strength or sealability. If there is any doubt about its quality, it should be verified by magnetic flaw detection, ultrasonic flaw detection and other methods.
High-pressure bend can be used cold simmering bend and hot simmering bend. 20-gauge steel pipe hot simmering bend, its hot bending temperature to 800 ~ 900 ℃ is appropriate, the heating temperature should not exceed 1050 ℃, the final bending temperature shall not be less than 800 ℃. Shall not use coal or coke heating, the application of charcoal for combustion, to avoid carburization. Heating temperature can be measured by thermocouple. In order to check the tube after bending for damage, after bending, should again be non-destructive flaw detection, such as defects, allowing grinding, grinding the minimum wall thickness should be not less than 90% of the nominal wall thickness.
Bending work such as after the thread processing, the thread and sealing surface should be taken to protect the measures.
High-pressure pipe bending jacket welding work, generally should be in the main bending and after the second flaw detection qualified.

High-pressure pipe bracket installation

The installation size and elevation of pipe support and hanger shall conform to the design provisions. The spacing of pipe supports and hangers shall conform to the design requirements and specifications. The installation of the bracket shall be level and firm.
The parts where the support and hanger are in contact with the pipe must be anticorrosive first, and then set up wooden frame, soft metal mat or rubber asbestos mat etc. in the middle of the pipe and the support and hanger according to the design or temperature requirement.
For high-pressure pipeline with thermal displacement, the boom should be installed in the opposite direction of displacement by half of the displacement value, and checked and adjusted again when the pipeline is put into thermal load operation.

Acceptance of high pressure pipeline handover

  • The handover shall be reviewed by the construction unit and the construction unit together to review the handover documents and information and conduct on-site inspection. The handover documents and information to be reviewed include
  • All certificates of the high-pressure pipe manufacturer.
  • Acceptance inspection registration form and calibration report form for high-pressure pipes.
  • Certificate of high pressure pipe processing.
  • All certificates of high-pressure pipe fittings, fasteners and valve manufacturers and calibration report sheets of fasteners
  • High pressure valve test certificate.
  • High-pressure pipe welding work records.
  • High-pressure pipeline test, blowing records.
  • Design modification and material substitution delivery information.

All the above information shall be submitted to the construction unit by the construction unit as delivery information. Acceptance should be inspected on site, including: whether the piping system after construction is consistent with the design drawings; whether the piping parts are complete, whether the bolts have been tightened one by one, and whether the piping has additional external force on the transmission equipment. The handover documents and information review and site inspection are qualified, and only after the single machine and linkage test operation can be put into operation.


Avoidance of oil pipes and fittings (including fasteners), etc. need to be degreased, should be degreased in accordance with the design proposed degreasing agent and requirements; when the design is not clearly specified, ferrous metal pipes, fittings degreasing agent should be used carbon tetrachloride; non-ferrous metal pipes, fittings degreasing should be used dichloroethane or industrial alcohol.
Before degreasing the pipe with obvious oil stains or serious rust, steam blowing or sandblasting should be used to remove the oil or rust spots.
Or when the degreasing agent used is carbon tetrachloride or dichloroethane, the surface of the pipe and fittings should be dried before degreasing.
Small diameter pipe degreasing is appropriate to use the immersion method, that is, the pipe into the tank with degreasing agent, soak 10 ~ 15min, in the middle should be turned 3 ~ 4 times, and then removed with dry compressed air or nitrogen without oil for purging, until the test passed.
Large smuggling tube degreasing is appropriate to use the infusion method, that is, the tube is placed vertically and diagonally, the mouth of the tube towards the bottom with a plug, from the mouth of the tube towards the top of the infusion of degreasing agent, the amount of infusion to more than 50% of the volume of the tube is appropriate, and then block the mouth of the tube, and put the tube down, rolling the tube every 3 to 4min, but 3 to 4 times after rolling, put off the tube degreasing agent, and then use the dry compressed air without oil blowing until the inspection is qualified.
Degreasing treatment of the outer surface of large-diameter tubes can be done by repeatedly wiping with degreasing agent after dipping in degreasing cotton cloth. Then place it in a well-ventilated place for more than 24h.
Check the method of degreasing with the grid. Inspection standards should be based on the different roles of degreased parts in production and the degree of danger or harm caused by contamination with grease, following the provisions of the following.
Directly or may be in contact with oxygen, rich oxygen, concentrated nitric acid and other strong oxidizing media, equipment, pipes, fittings, valves, etc., can be inspected using any of the following methods.

  • a. Using wavelength work 3200 ~ 3800 λ ultraviolet ray to check the surface of the degreased parts, no oil fluorescent light for qualified.
  • b. Wipe the surface of the degreased parts with clean and dry white filter paper (the inner wall of the pipe), no traces of grease on the paper for qualified.
  • c. With oil-free steam blowing degreasing parts, take its condensate, put a small grain (below 1mm diameter) of pure camphor, to camphor grains keep rotating as qualified.
  • d. Can not be tested with the above methods of degreasing pieces, can be taken from the degreasing solvent samples, grease content shall not exceed 350mg / L for qualified.

The pipeline with concentrated nitric acid should analyze the total amount of organic matter contained in the acid to not more than 0.03% as qualified.
Degreased parts with solvent degreasing must be thoroughly blown out the residual solvent until there is no solvent smell. Degreased with lye must be cleaned with oil-free water rinse to neutral, and then dry. Blown out with steam, should be timely degreased parts dry. Oil-free water used to rinse austenitic stainless steel, the chloride ion content shall not be greater than 25ppm.
Design inspection standards, should be tested according to the standards specified in the design.

Test pressure

Pipeline test pressure requirements, according to the nature of its input medium, pressure, temperature and other parameters due to some reason the design unit or construction unit to determine. If there are no specific provisions, the pressure test can be conducted at 1.25 times the generated pressure for 10 minutes, no leakage for qualified.

Pipeline oil cleaning

Oil cleaning in the form of oil circulation, circulation process every 8 hours in the range of 40 ~ 70 ℃ is appropriate to repeatedly lift the temperature 2 ~ 3 times.
Oil cleaning should be used for the equipment of high quality oil. After cleaning the qualified pipeline, should take effective protection measures. Before the test run should be replaced with the official oil with a certificate of conformity.
Oil cleaning qualified standards when the design or manufacturing plant does not require, the pipeline oil cleaning with a filter check, qualified standards should be in accordance with the provisions of Table.14.
Table.14 oil cleaning qualified standards

Equipment speed(r/min

Filter screen specification (mesh)

Qualification criteria



Visually inspect the filter screen, and the residual dirt within each square centimeter shall not be more than 3 particles



Quality standard

Guarantee items

The type, specification and quality of pipes, components and welding materials must meet the design requirements and specifications.
Inspection method: check the certificate of conformity, acceptance or test records.
Valve specifications, models and strength, tightness test and the need for disassembly inspection of the valve, must comply with the design requirements and specifications.
Pressure, gas and tightness test, within the specified time must meet the design requirements and specifications.
Inspection method: check the sectional test records by system. Full inspection by system.
Weld surface shall not have cracks, burn-through, nodules and serious slag, porosity and other defects. There are special requirements of the weld, must comply with the provisions.
Inspection method: Observation check with a magnifying glass. Weld joints with special requirements, check the test records. Randomly check 10% by the number of interfaces in the system, but not less than 5.
The surface of the pipe mouth flange must not have defects such as wrinkles, cracks and scratches.
Inspection method: observation check. 10% random inspection by the number of interfaces of the system, but not less than 5.
The pipes, parts, accessories, gaskets and packing of degreasing and avoiding oil must meet the design requirements or specification after degreasing.
Inspection method: Check the records of degreased fatty acid. Check all by system.
The surface of the bend must not have defects such as cracks, delamination, pits and over-burning.
Inspection method: 10% by system random inspection, but not less than 3 pieces.
Weld flaw detection inspection: brass gas welding seam of the radiographic flaw detection must be tested according to the number of design or specification. Working pressure of 10MPa or more, must comply with the provisions of Schedule 1, item 2, working pressure of 10MPa or less, must comply with the provisions of Schedule 1, item 3.
Inspection method: check the flaw detection records, if necessary, 10% of the number of weld ports can be sampled according to the required inspection.
Weld mechanical properties inspection: the mechanical properties of welded joints must comply with the provisions of Schedule 2.
Inspection method: Check the test records.
The cleaning and blowing of the piping system must be cleaned and blown according to the design requirements and specifications.
Inspection method; check the cleaning and blowing records. Check all by system.

Basic items

The installation position of the support, hanging and bracket is correct, level and firm. The bracket should be separated from the pipe by asbestos sheet, soft metal pad or wooden pad, and the contact is tight. The movable surface of the movable bracket is in good contact with the supporting surface and moves flexibly. The hanger rod should be vertical and the wire buckle should be complete. Rust and dirt should be removed, paint evenly, no leakage and good adhesion.
Inspection method: Hand pulling and observation inspection. Randomly check 10% of the pieces of support and hanger brackets according to the number of pieces in the system, but not less than 3 pieces.
The slope of the pipe shall conform to the design requirements and specifications.
Inspection method: check the measurement records or use level meter (level) to check. According to the system every 50m straight pipe section sample check 2 sections, less than 50m sample check a section. There are partition walls can be segmented by partition walls.
Compensator installation: The two arms of type II compensator should be straight, should not be distorted, and the outer arc is uniform. Horizontal pipeline installation, the slope should be consistent with the pipeline. The direction of waveform and packing type compensator installation should be correct.
Inspection method: Observation and inspection with horizontal ruler. Check all by system.
Valve installation location, direction should be correct, the connection is solid and tight. The operating mechanism is flexible and accurate. Valves with special requirements should comply with the relevant provisions.
Inspection methods: observation and make revelation recording closed check or check the commissioning records. According to the type of valves in the system 10% of each sample check, but not less than 2. Valves with special requirements should all be checked.
Flange connection: butt should be tight, parallel, coaxial, and perpendicular to the centerline of the pipe. Bolts should be evenly stressed and exposed nuts 2 ~ 3, gaskets installed correctly. Loose sleeve flange pipe mouth flange bend for rounded corners, the surface is free of creases, cracks and scratches.
Inspection methods: screw test with a wrench, observation and check with a ruler. Check 10% of each flange type according to the system, but not less than 3 places, and all flanges with special requirements should be checked.
Allowable deviation items (Table.15 ~ Table.17).
Table.15 Allowable deviation and inspection method of copper and brass piping installation works



Allowable deviation

Inspection method


Straightness of welded junction

Pipe wall thickness(mm


1/3 of pipe wall thickness

Check with ruler and sample ruler




Reinforcing layer of weld



Check with welding inspection ruler




Bite meat





Continuous length


Check with ruler and welding inspection ruler

Total length (both sides)

Less than 25% of weld length


Coordinates and elevation




Check the measurement records or measure with theodolite, level gauge (level ruler), straight edge and ruler

Trench and overhead







Table.16 (continued) Allowable deviations and inspection methods for copper and brass piping installation works

5 Longitudinal and transverse bending of horizontal pipeline DN≤100mm 0.001 Max. 20mm Check with a level, straight edge and stay wire
DN>100mm 0.0015
6 Verticality of riser 0.002 Maximum 15mm Check with a ruler and a level and a lifting line
7 Row pipe section On the same plane 5mm Check with ruler and stay wire
Spacing +5mm
8 Overlapping Pipe outer wall and insulation layer +10mm Check with ruler
9 Ovality of bend Red copper 9% Check with ruler and external caliper
Brass 8%
10 Bending angle of bend (Note 3) PN≤10MPa Per meter ±3mm Check with sample plate and ruler
PN>10MPa Longest ±10mm
Per meter ±1.5mm
11 Wrinkle unevenness of bend PN<10MPa 2mm Check with ruler and external caliper
12 Overall dimension of type II compensator Cantilever length 10mm Check with ruler and stay wire
Straightness Per meter ≤3mm
Overall length ≤10mm
13 Pretension length of compensator II shape ±10mm Check pre stretching record
Packing type, waveform ±5mm

Table.17 Flaw detection inspection standards for pipe welds

Item Quality inspection standard
Crackle Incomplete fusion Incomplete penetration Stoma Slag inclusionmm
Wall thicknessmm Quantity Length of single strip slag inclusion Total length of strip slag inclusion Strip slag inclusion spacing
1 Not allow Not allow Not allow 2.05.0 02 Not allow Not allow Not allow
5.010.0 23
10.020.0 34
20.050.0 46
2 Not allow Not allow No more than δ The maximum length shall not exceed 2mm, and the length shall not exceed the total length of slag inclusion 2.05.0 24 1/3 δ However, the minimum can be 4 and the maximum can not exceed 20 At 12 δ The length shall not exceed δ Or no more than the length of single strip slag inclusion in any length 6L, when the spacing is less than 6L, the total length of slag inclusion shall not exceed the length of single strip slag inclusion
5.010.0 46
10.020.0 68
20.050.0 812
3 Not allow Not allow No more than δ 15%, the maximum shall not exceed 2mm, and the length shall not exceed the total length of slag inclusion 2.05.0 36 2/3 δ But the minimum can be δ Max. 30 At 6 δ The length shall not exceed δ Or no more than a single strip slag inclusion length in any length 3l, when the spacing is less than 3l, the total length of slag inclusion shall not exceed the length of single strip slag inclusion
5.010.0 69
10.020.0 912
20.050.0 1218

Table.18 Copper, brass welded joints mechanical properties table (TJ307-77)

Item Project
1 Tensile strengthσb(MPa) Brass gas welding PN≤10MPa 200350
PN10MPa 330350
2 Cold bending angle α Brass gas welding PN≤10MPa D=2s≥120°
PN10MPa D=2s,≥180°
3 Normal temperature impact valueJ/cm2 Brass gas welding PN10MPa > 100
4 Shear strength σ(MPa) Material 301 Copper-copper brazing > 160
Brass-brass brazing > 160
Material 302 Copper-copper brazing > 180
Brass-brass brazing > 180
Material 601 Copper-copper brazing > 250
Brass-brass brazing > 250
Material 603 Copper-copper brazing > 220

Protection of finished products

After pickling or passivation, or degreasing qualified pipes, effective protection measures should still be taken before installation.
When interrupting the construction, the mouth of the pipe must be ready for temporary closure; when sealing the installation, pay attention to check whether there are foreign objects in the pipe.
The pipeline laid in the trench, before construction to clean up the slag, dirt in the trench; strictly prohibited to have installed the pipeline stomp, and timely cover the trench cover.
Bending work should be carried out after thread processing, and protective measures should be taken for the thread sealing surface.
The brackets installed on the wall, concrete column and in the trench are suitable for pre-set holes or pre-buried iron parts during the construction of building works, and should not be arbitrarily drilled to avoid damaging the building.
When installing pipes, the surface of pipes should be prevented from being scratched by gravel or other hard objects.
 Before the acceptance, the construction unit should be specially organized to protect the finished products, 24h when someone is on duty. And to lock the building where the construction is located at any time.
Pipes and fittings should be properly stored in the construction, not to be confused and damaged. Contact with carbon steel should be avoided.

Quality issues that should be noted

The cutting and beveling of copper pipes can only be done by cold working method.
The inner and outer surface of the tube should be smooth, clean, without pinholes, cracks, wrinkles, layering, roughness, pulling channel, slag, bubbles and other defects. Brass tube shall not have green rust and serious dezincification.
Brass tube with roundness, should not exceed the allowable deviation of the outer diameter. The end of the tube shall be flat and burr-free. The inner and outer surface of the tube shall not have defects such as local pits, scratches, pressed-in objects and bruises that exceed the allowable deviation of the outer diameter and wall thickness.
The copper pipe connected by flanging shall maintain the coaxiality, and its deviation shall be: DN≤50mm, not more than 1mm; DN>50mm, not more than 2mm.

Quality records

  • There shall be factory certificate of conformity of materials and equipment.
  • Records of incoming inspection of materials and equipment.
  • Pre-inspection records of dry pipe.
  • Pre-inspection records of riser pipe.
  • Single pressure test records of pipelines.
  • Concealed inspection records of pipelines.
  • System pressure test records.
  • System flushing records.

Safety and environmental protection measures

The six disciplines of safe production must be observed when entering the site.
When pulling the temporary power supply, the electric wire should be overhead, and the aisle should be protected by steel pipe, so that the electric wire will not be run over by cars and objects.
Electrical equipment in the box should be intact, with special leakage protection switch, must be set up according to “a machine a gate a leakage a box” requirements.
All mobile electrical equipment, should have two leakage protection, no damage to the wire, the plug socket should be intact, it is strictly prohibited to use the plug and plug the wire directly into the socket.
All types of electrical machinery should be diligent maintenance, timely cleaning, oiling, in use, such as in the event of a power failure or temporary departure, must close the door or unplug.
When using the cutting machine, first check the integrity of the protective cover, the rear part is strictly prohibited to have flammable and explosive substances, cutting machine shall not replace the grinding wheel to grind things, cutting machine is strictly prohibited to cut hemp wire and wood blocks.
When simmering bend, first check whether there are explosives in the coal, sand drying, to prevent explosions. Sand filling table set up firmly . To prevent the collapse of injuries.
In the high ladder, scaffolding to install the pipe, must pay attention to the solidity of the foothold. When using pipe pliers to install the pipe, one hand to hold the head, a palm hold the handle of the pliers, slowly plate snap, do not use both hands to hold the handle of the pliers, vigorous plate snap, to prevent the mouth slipping out of control fall.
Site excavation of pipe ditch or deep pit, according to the soil conditions should be set up to prevent the collapse of the retaining plate. If the soil quality is poor, the pipe pit full 1m deep, should be used to support or slope. The trench or pit shall be clearly marked. When digging near the cable, prior contact with the relevant departments shall be made and safety measures shall be taken before construction.
Material room and dressing room shall not use more than 60w light bulb, and the use of iodine tungsten lamp and household electric heater (including electric stove, electric cup, heaters, electric rice cooker) for heating, boiling water and cooking is strictly prohibited.

Source: Network Arrangement – China Copper Pipes Manufacturer – Yaang Pipe Industry Co., Limited (

(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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