The standard practices of 7 connection modes of building pipelines are summarized!

Thin wall stainless steel pipe compression connection compression joint assembly insertion depth compression connection ring compression connection 6 hot melt connection clean the hot melt part and mark the hot melt depth of socket connection.

Weld groove, assembly size, weld assembly method, weld assembly misalignment correction, pipe weld misalignment ➤ welding 1) stainless steel pipe welding is internally filled with argon for protection, and the weld and heat affected zone are pickled and passivated after welding; 2) Copper pipe brazing shall not be heated excessively (650-750 ℃), and the residual slag and other sundries at the welded joint shall be removed after welding; 3) The weld appearance shall be free of defects such as meat biting, slag inclusion, crack and splash.

Distribution position of main dimensions on conical external thread, basic dimension and tolerance of thread · national standard 55 ° sealed pipe thread (GB / t7306), which is applicable to the threaded connection of pipes, valves, pipe joints, cocks and other pipeline accessories.

After the stainless steel pipe is welded, the weld shall be brushed with stainless steel brush dipped in acid paste until it is white and bright, and then washed with clean water; Then wipe it with passivation solution, scrub it with cold water, and finally rinse it with hot water and dry it.

Groove processing dimensions basic dimensions and deviation table of steel pipe rolling groove and slotting time standard for processing a groove groove groove too deep steel pipe groove processing ➤ groove assembly 1) clean the pipe end, put on the rubber sealing ring, install the clamp and fasten the bolt; 2) The center lines of the pipes at the two ends of the trench shall be consistent, and the installation direction of the trench (position of fastening bolts) shall be consistent; 3) Rigid joints should be used for straight pipe sections, and a flexible joint should be set between every 4-5 continuous rigid joints on the pipe section.

The spacing shall be ≯ 150mm, and the outer end shall be ≯ 100mm from the edge of the air duct.

Clamp and connect, clean the insertion port and mark the insertion depth.

Installation drawing of socket flexible interface flexible cast iron pipe flange connection flexible cast iron pipe joint sleeve connection common problem example two pipe sections are not straight..

Common problems of bracket installation at both ends of groove joint example: the direction of groove joint is not uniform, and the pipes at both ends of groove are not smooth and straight.

The application width of red lead shall be consistent, the coating shall be uniform, and there shall be no flowing and missing coating.

In case of broken or missing thread, it shall not be greater than 10% of the total number of threads.

Use a special hot-melt machine to heat the connecting parts according to the specified heating time.

Flange connection ➤ pipe flange 1) the specification and model of companion flange are the same; When connecting with the equipment flange, it shall be matched according to its specification; 2) The flange connection shall be coaxial and parallel, and the flange surface shall be perpendicular to the pipe center;   3) The fastening bolts have the same specification, the same direction, and the exposed length of the bolt is 1 / 2 of the bolt diameter or flush with the nut; 4) When connecting the valve, put the nut on the valve side; 5) The top two screw holes of the horizontal pipe flange shall be kept horizontal, and the two screw holes of the vertical pipe flange close to the wall shall be parallel to the wall· Flange standards: national standard gb9112-9123, standard jb79-86 of the Ministry of machinery, standard hg5008-5028 of the Ministry of chemical industry and standard syj4 of the Ministry of petroleum industry.

Schematic diagram of argon filling for stainless steel pipe welding the appearance of copper pipe brazing connection weld is well formed common problems example: the brazed weld of copper pipe is not cleaned, the undercut of stainless steel pipe weld is not treated, the weld width is different, and the reinforcement is different.

The material specification of rectangular air duct angle steel flange angle steel flange connecting metal air duct flange shall not be less than the provisions in the following table: ➤ air duct sheet steel flange 1) the flange shall be vertical and close to the air duct; 2) Apply sealant on the inner and outer sides of the four corners of the air duct flange for sealing; 3) The four corners of the flange shall be fixed with bolts, and the middle shall be clamped with spring clips or jacking screws.

The thread shall also meet the requirements of assembly tolerance and have a taper of 1 / 16 to prevent loose or tight fit between threads.

Plastic pipe hot-melt socket connection technical parameters of plastic pipe hot-melt socket connection plastic pipe hot-melt butt connection 7 socket connection before connecting cast-iron pipe, clean the sundries affecting the tightness of the interface at the socket and correctly place the rubber sealing ring.

Welding profile of flange and pipe common problems of bolt direction and length specification for automatic welding of flange and pipe example: the inner ring of flange is not welded, the bolts on both sides are not aligned, and the flange does not match ➤ air duct angle steel flange 1) the flange shall be made with flat flange surface, equal diagonal length and full weld; 2) The spacing between flange bolt holes and rivets shall be uniform and meet the specification requirements, and screw holes shall be set at the four corners of the flange; 3) During flange connection, the bolt direction shall be uniform and the length shall be consistent, and the bolt material shall correspond to the air duct; 4) The flange shall be tight without leakage after fastening, the flange surface clearance shall be uniform, and the gasket shall not protrude into the pipe or out of the flange; 5) The bolts are free of corrosion after flange connection· The hole spacing of bolts and rivet holes of air duct flanges of medium and low pressure systems shall not be greater than 150mm, and that of air ducts of high pressure systems shall not be greater than 100mm.

Use the special clamping tool to clamp the joint.

Text:   Summarize the seven common connection methods of building pipelines, and share the construction standards and practices of each method for allies’ reference! 1 threaded connection ➤ the thread shall be cut in 2-3 times.

After copper pipe welding, when the solder is fully solidified but not completely cooled, wipe the flux left at the weld with return wire and clean water, and dry the return wire.

➤ the misalignment of the inner wall of the weld assembly shall not exceed 10% of the wall thickness and ≯ 2mm; The misalignment of outer wall is ≯ 3mm.

When using, pay attention to the different number of bolt holes of individual flange specifications.

After clamping, use the gauge to check whether the clamping size is in place.

The pipe diameter of JB standard and Hg standard is “small outer diameter”, and that of GB standard and SYJ standard is “large outer diameter”.

The thread shall be clear, complete and smooth without burr and messy wire.


Insert the pipe according to the specified depth and keep the axis vertical.

Then apply clear paint on the weld for one time to prevent corrosion.

4 groove connection ➤ groove processing 1) check the nozzle size, roundness and manufacturing quality, which shall meet the requirements of groove fabrication; 2) The groove shall be processed by times according to the specified time, and the depth and other dimensions of the groove shall be retested; 3) The groove processing shall not damage the galvanized layer and inner coating of the pipe.

Halfen Channel

Common problem example: Hemp wire is not cleaned, exposed thread is long and painted according to the specification, and exposed thread is painted at will.

The four corners of the rectangular air duct flange shall be provided with screw holes.


➤ after thread assembly and tightening, expose 2-3 thread tails, remove excess filler, and brush exposed thread teeth with red lead for rust prevention.

Insert and maintain the verticality of the two pipe sections according to the depth required by the construction standard.

Sealing method of four corners of conjoined flange installation angle connection diagram of air duct of steel sheet conjoined flange spring clamp fixed spring clamp distribution diagram of air duct connected with top screw clamp fixed top screw clamp distribution diagram of air duct connected with angle steel flange connection bolt direction and length are unified, and the fixed spacing between spring clamp (left) and top screw clamp (right) is uniform 3 welding connection ➤ weld groove shall be in accordance with the specification requirements, It is generally V-shaped, the groove angle is 60-75 °, and the assembly clearance is 2-3mm.

The center of flange bolt hole is the same.

After heating, the joint shall be fused according to the specified pressure and time, and a uniform fusion ring shall be formed at the joint.


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