Welded pipe

Pipe, welding material (baking, insulation), welding treatment (cleaning, break type), welding precautions (current, voltage, gas welding wind, rain and snow weather)

Pipe welding and inspection

① Welder welding according to welding operation instructions;

② Welders must hold a certificate to work, shall not exceed the time of welding;

(3) Before welding, the dirt on the surface and edge of the groove should be cleaned up within a range of not less than 20mm;

④ Welding materials shall be baked, insulated and distributed according to the requirements of welding operation instructions;

(5) Arc welding should be carried out in the groove, strictly prohibited in the pipe wall arc;

NG process pipeline using welding rod arc welding, CNG process pipeline using argon arc welding method, the previous layer is not welded to the next layer, in the welding should ensure the arc and arc recovery quality, arc recovery should be filled, the indirect head of the layer should be staggered;

In addition to the special requirements of the welding process, each bead should be welded once. If it is interrupted for some reason, anti-crack measures should be taken. When welding again, it must be checked to confirm that there is no crack before continuing welding;

⑧ After welding each weld, the welder's mark steel number should be made with a marker pen in the easily observed part of the weld edge, and fill in the "welding record";

⑨ Welding should be stopped in the following environments (when no protective measures are taken)

a, electrode arc welding, the wind speed is equal to or greater than 8m/s;

b, gas shielded welding, the wind speed is equal to or greater than 2m/s;

c, relative humidity is greater than 90%;

D. Rainy weather.

⑩ The surface quality of the welded joint should meet the following requirements:

a, there should be no cracks, no fusion, porosity, slag inclusion, splashing;

b, the weld is not allowed to bite the edge.

c, weld surface shall not be lower than the pipe surface, weld residual height △h should meet the following requirements:

(1) 100% ray detection of welded joints, its △h≤1+0.1b1, and not greater than 2mm;

② Other welded joints, △h≤1+0.2b1, and not more than 3mm;

③ The height of the fillet weld is not lower than the thickness of the thinner part;

Note: b1 is the large width of the welded joint group to the rear groove, mm;

After the weld inspection is completed, fill in the "weld appearance quality inspection Record".

GB50236-98 Field equipment, industrial pipeline welding engineering construction and acceptance