5.2　Installation of High Pressure Pipes

5.2.1　The installation of pipes shall meet the following requirements.

1　The quality of fit-up shall meet the requirements of Clause 5.1.9.

2　When fitting up,the direction and location of stubs,holes or blocks on the pipe assembly shall be in accordance with the requirement of drawing.

3　Striking arc,testing electric currents or welding temporary supports shall be forbidden on the surface of alloy steel pipes.

4　When fitting up the pipes with thick wall and large diameter,the additive with same material quality shall be fixed in the groove after the fit-up of pipes reached the requirement(see Figure 5.2.1).If no additive with same material quality available,surfacing welding with same material quality shall be performed between the additive and the base material.The surfacing shall be no less than 2 layers.When the temporary additives are removed,the base metal shall not be hurt.The remaining welding scar shall be removed and trimmed.

5　If pipe segments for the adjustment is designed,the neighboured pipes shall be adjusted to meet the requirement of drawing.The pipe segments for the adjustment shall be prepared according to the actual dimension and fitted up without strong force.

6　After installing the whole system,PMI marks on alloy steel pipes shall be checked.If no mark is available,PMI shall be carried out and the test report shall be provided.The other alloy pipe segments shall also be marked.

5.2.2　When installing steam conducting pipe,its inner surface shall show metallic luster without sundries inside.

5.2.3　When aligning the partial section of alloy steel pipe,the heating temperature shall be controlled below Ac1.

5.2.4　The installation of the expansion indicator,the supervision segment and creep measurement points shall meet the following requirements.

1　The pipe expansion indicator shall be correctly installed in line with the design requirements.It shall be adjusted to zero in the cold conditions before the flushing of pipes.

2　The supervising section in the steam pipe shall be installed according to the design requirements.The pipe with largest minus tolerance among the same lot of the pipe shall be selected as the supervising segment.There shall be no openings,instrument sockets or supports and hangers on the supervising section.

3　The creep measurement points shall be installed before flushing the pipes.

4　The radial distance between symmetrical creep measurement points for the same nominal diameter pipe shall be the same.The deviation value shall be less than 0.1mm.

5　The following measurement shall be carried out and recorded in cooperation with the owner.

1)The wall thickness on both ends of the supervision section.

2)The primary radial distance between each pair of symmetrical creep measurement points.

3)The outer diameter or the circumference of the pipe where the creep measurement point is installed.