Installation and construction steps of copper pipes

Process overview

The installation and construction of copper pipes should be developed before the start of the scientific process to ensure that the construction process is up to standard. Share the installation and construction steps of copper pipes commonly used in our factory.

Copper pipe straightening → cutting → pipe prefabrication → pipe installation → pipe pressure test → insulation → pipe flushing → system water

20211012105814 61444 - Installation and construction steps of copper pipes

The installation steps of copper pipe detailed explanation

Straightening of copper pipes

  • (1). Copper channel straightening should be filled with sand, and then straightened with a straightener; sand-filled copper pipe can also be placed on a flat plate or workbench, and lay a wooden mat on it, and then rubber hammer, wooden hammer or square wood along the body of the pipe gently knocked, straightened section by section.
  • (2). 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. After straightening, the residual sand inside the tube should be cleaned up.

Cutting of copper pipe

  • (1). Copper pipe cutting can be used hacksaw, wheel saw cutting, but shall not use oxygen – acetylene flame cutting. Copper cutting, should prevent improper operation and deformation of the tube, the end face of the tube incision should be perpendicular to the axis of the tube, the burr at the incision should be cleaned up.
  • (2). Copper pipe bevel processing using a file or beveling machine, but shall not use oxygen – acetylene flame to cut processing. Clamp the copper pipe vise jaws on both sides should be padded with a wooden board liner to prevent pinching the pipe.

Pipe prefabrication

  • (1). According to the size of the processing chart, the connection method used, calculate the length of the pipe section (including the length of the inserted fittings and the length occupied by the fittings) to cut the copper pipe material.
  • (2). Pipeline construction conditions for ground prefabricated pipeline, without affecting the premise of on-site installation, as far as possible, copper pipe, tee, elbow, reducer and other pipe fittings prefabricated into the required complete pipe section before installation; installation of the compensator, it is appropriate to connect the compensator with the adjacent pipeline prefabricated pipe section before installation; should be prefabricated as far as possible into the appropriate length of the pipe section before installation; multiple pipelines laid in parallel, should Try to make the pipeline neat and beautiful.

Installation of bracket and pipeline

(1) According to the pipeline direction, length, pipe fittings and the location of the compensation device, set the corresponding fixed bracket and general common bracket, the card frame model should be matched with the pipe to ensure that the card frame is installed smoothly and firmly, fixed bracket, coordinate position must be accurate and reasonable to ensure the compensation effect. When steel bracket is used, 3㎜ thick asbestos rubber mat is added between pipe and bracket. The spacing of copper pipe movable bracket is shown in the following table.

Nominal internal diameter
15 20 25 32 40 50 65 80 100 125 150 200
Vertical Piping 1.8 2.4 2.4 3.0 3.0 3.0 3.5 3.5 3.5 3.5 4.0 4.0
Horizontal piping 1.2 18 1.8 2.4 2.4 2.4 3.0 3.0 3.0 3.0 3.5 3.5

(2) Prefabricated pipe sections will be adopted to connect pipe fittings, and through the selected installation method, the pipe sections will be connected into complete pipeline according to the design requirements, and fixed on the support and hanger to become a complete pipeline system. After the installation of copper pipe, it should meet the design requirements and construction specification standard requirements, and ensure that the pipe is straight and horizontal.

The main points of copper pipe welding operation

20211012091341 86126 - Installation and construction steps of copper pipes

Copper pipe welding operation points
The outer surface of the copper pipe, welding fittings inside and outside the surface of the oxide film and oil, debris clean. After evenly brushing brazing agent on the outer surface of the pipe and the inner surface of the pipe fitting, insert the copper pipe into the pipe fitting to the bottom and rotate it appropriately to maintain an even gap and remove the excess brazing agent. Select the appropriate torch according to the specifications of the copper pipe fitting. Use a neutral flame to heat the socket portion of the copper pipe joint being welded. Use gas welding flame to heat the joint evenly until 750-850℃, then contact the heated joint with brazing material, melt the brazing material with high temperature at the pipe joint, the brazing material melts rapidly and flows along the joint gap into the joint, add brazing material while heating until the weld is filled. (After ignition, the flame intensity is adjusted to 30-35mm from the gun barrel mouth, the flame center is about 12-15mm from the socket of the welded parts, and the whole socket is heated evenly (the socket has been assembled before), and after about 30-40 seconds, the color of the surface of the socket starts to turn white and the “wet” feeling starts to appear near the flame area, and the flame intensity is adjusted to 25-30mm from the gun barrel mouth. Adjust the flame intensity to 25-30mm from the barrel mouth, melt a small amount of brazing material into the weld mouth, when the brazing material in the weld formation area quickly spread to both sides, forming a white and clear molten pool, quickly match the brazing material with the welding area, so that it melts and penetrates into the assembly gap to form the weld. (When adding brazing material, the torch should swing back and forth around the molten pool with the brazing material to encourage the brazing material to flow and fill the entire weld area.) Do not heat the brazing material directly with the flame. After stopping the heating, let the joint cool and crystallize at rest. After finishing the welding, clean the residue at the joint with hot water, and you can spray varnish to protect it.

  • (1). Pipe connection should be reconfirmed before the pipe connection whether the specification size of pipe and fittings meet the connection requirements.
  • (2). According to the design drawings on-site actual measurement of the length of the piping, the lower material should be accurate. Cutting available rotary pipe cutter or per centimeter not less than 13 teeth of the hacksaw or chainsaw vertical cutting, cutting should remove the burr inside and outside the pipe mouth and rounding.
  • (3). Brazing strength is small, the general welding mouth using lap form. The lap length is 6-8 times of the pipe wall thickness, and the lap length is (1.2-1.5)D(㎜) when the outer diameter D of the pipe is less than or equal to 28㎜.
  • (4). Before welding, the outer wall of copper pipe and the inner wall of pipe fitting should be rubbed with fine sandpaper, steel brush or cloth sandpaper containing other abrasives to remove surface oxides.
  • (5). Welding process, the welding gun should be properly selected according to the size of the diameter of the pipe, the connection of the socket and welding rod should be heated evenly. Welding, there shall be no overheating phenomenon, welding material seepage full of welding seam should immediately stop heating, and remain stationary, natural cooling.
  • (6). When welding between copper pipe and copper alloy fittings or copper alloy fittings and copper alloy fittings, flux should be used at the welding of copper alloy fittings and the residual flux on the outer wall of the pipe should be removed after the welding is completed.
  • (7). When welding copper-plastic pipe, the length of bare copper pipe should be peeled out not less than 200mm, and the wet cloth should be wrapped around both ends, and the plastic-plastic layer should be recovered after the welding is finished.
  • (8). After welding, the pipe fittings must be cleaned within 8 hours to remove the residual flux and slag. Commonly use boiled alum solution containing 10-15% or citric acid solution containing 10% to brush the joint, and then rinse and dry with water.
  • (9). Welding installation should try to avoid upside-down welding.

Flange connection

Use loose flange when connecting the pipe and valve, etc. The sealing gasket between copper flange adopts 4㎜ asbestos rubber sheet.

Water pressure test

(1). After the installation requirements of concealed and embedded pipes meet the installation regulations, the test pressure can be carried out.
(2). The test pressure is 1.5 times of the working pressure of the pipeline system, but not less than 0.6MPa.
(3). Before the hydraulic test, the test pressure pipe should take safe and effective measures to fix and protect. The joint parts for the test should be exposed.
(4). After passing the hydraulic test, the civil construction can be carried out.
(5). Hydraulic test should be carried out in accordance with the following steps.

  • ① The end of the test pressure pipe section blocked, slowly inject water, water injection process, while the gas in the pipe will be exhausted.
  • ② After the pipeline system is filled with water, the water tightness check.
  • ③ Pressurization of the system is appropriate to use manual pumps to slowly ramp up the pressure, the ramp-up time should not be less than 10min
  • ④ After rising to the specified test pressure, stop pressurization and observe for 10min, the pressure should be reduced by not more than 0.02MPa.
  • ⑤ After dropping to the working pressure for inspection, there should be no seepage or leakage.
  • ⑥ After the test pressure of piping system, if water leakage or pressure drop exceeds the specified value is found, the piping should be checked and the cause of water leakage should be excluded, and then the test pressure should be retested according to the above provisions until it meets the requirements.

(7) In winter, when the temperature is lower than 5℃, reliable anti-freezing measures should be taken when conducting water pressure test and water flow capacity test.

Pipe insulation

Insulation is carried out after the water pressure test of pipeline system is passed. 20㎜ thick rubber insulation shell is used for cold water pipeline to prevent condensation. The insulation thickness of hot water pipeline refers to the following table.

Nominal internal diameter
15 20 25 32 40 50 65 80 100 125 150 200
Thickness of insulated pipes
25 25 30 30 30 30 35 35 35 35 40 40

Flushing of pipeline system

  • (1). After the pipeline passes the test pressure, it should be flushed with clean water until the dirt is flushed out. Before flushing, the instrument inside the system should be protected, and the orifice plate, nozzle, strainer, throttle valve and check valve and other parts that hinder the flushing work should be removed and properly stored, and be reset after flushing.
  • (2). Drinking water pipeline should be disinfected before use, after disinfection and then flush the pipeline with drinking water, and the water quality is not contaminated by the relevant departments to take samples to test before use.

Post-construction testing

Quality standard

(1). Guarantee items.
① 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.
② Valve specifications, type and strength, tightness test and the need for disassembly inspection of the valve, must comply with the design requirements and specifications.
③ Hydraulic test 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.
④ The surface of the weld must 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. 10% by the number of interfaces of the system sampling, but not less than 5.
⑤ The surface of the pipe mouth flange must not have defects such as wrinkles, cracks and scratches.
Inspection method: observation inspection. Check 10% of the number of interfaces by the system, but not less than 5.
⑥ Bend pipe surface shall not have cracks, delamination, pits and over-burning and other defects.
Inspection method: 10% random inspection by system, but not less than 3 pieces.
⑦ Mechanical properties of the weld inspection: the mechanical properties of the welded joint must comply with the provisions of Schedule 2.
Inspection method: Check the test records.
⑧ The cleaning of the piping system must be cleaned according to the design requirements and specifications.
Inspection method: Check the cleaning records. Check all by system.
(2). Basic items
① Support, hanging, bracket installation position 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. According to the number of pieces of support, hanger brackets in the system 10% sample check, but not less than 3 pieces.
② The slope of the pipe should meet the design requirements and specifications.
Inspection method: check the measurement records or level meter (level) check. According to the system every 50m straight pipe section sample check 2, less than 50m sample check a section. There is a partition wall can be segmented by the partition wall.
③ 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 the waveform and filler or compensator installation should be correct.
Inspection method: Observation and inspection with horizontal ruler. Check all by system.
④ The valve installation position and direction should be correct, and the connection should be firm and tight. The operating mechanism is flexible and accurate. Valves with special requirements should comply with the relevant provisions.
Inspection methods: observation and opening and closing inspection or check the commissioning records. According to the type of valves in the system 10% of each sample check, but not less than 2. All valves with special requirements should be checked.
⑤ Flange connection: The butt joint should be tight, parallel, coaxial, and perpendicular to the centerline of the pipe. The bolt should be evenly stressed and the nut should be exposed by 2~3㎜, and the gasket should be correctly installed. The flanges of loose set flanges should have rounded corners at the flanging and bending places, and the surface should be free of creases, cracks and scratches.
Checking method: test with wrench, observe and check with ruler. According to the type of flange in the system, 10% of each flange should be randomly checked, but not less than 3 places, and all flanges with special requirements should be checked.

Protection of finished products

  • (1) Interrupt the construction, the mouth of the pipe must be ready for temporary closure work; seal installation, pay attention to check whether there are foreign objects in the pipe.
  • (2) Bending work after the thread processing, the thread sealing surface should take protective measures.
  • (3) Installed in the wall, concrete column on the bracket, it is desirable to cooperate with the construction of building works with the reserved hole or pre-buried iron, should not be arbitrary hole, so as not to damage the building.
  • (4) Pipeline in the installation, should prevent the surface of the pipeline by gravel or other hard objects scratch.
  • (5) Before the acceptance, the construction unit should be specially organized to protect the finished product, 24h when someone on duty. And to keep the building where the construction is closed and locked.
  • (6) Pipes and fittings should be properly stored in the construction and should not be confused and damaged. Contact with carbon steel should be avoided.

Quality issues that should be noted

  • (1) The cutting and beveling of copper pipes can only be done by cold processing.
  • (2) The inner and outer surface of the tube should be smooth and clean, and there should be no pinholes, cracks, wrinkles, layering, roughness, pulling channels, slag, bubbles and other defects.
  • (3) The ellipticity of the copper tube should not exceed the allowable deviation of the outer diameter. The end of the tube should 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, bruises, etc. that exceed the allowable deviation of the outer diameter and wall thickness.

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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