5.10 Installation of Large-diameter coil-welded steel pipe
Ⅰ Dominant Items
5.10.1 The deformation and peeling of paint on steel element due to handling，piling and hoisting shall be corrected and repaired.
Check quantity:10% random check for elements and at least 4 pieces.
Check method:observe or pull line and check with a steel rule.
5.10.2 The pipe shall have no residual or dirt inside after installation.
Check quantity:full check.
Check method:check the records for concealed works or take visual check.
5.10.3 The position and direction of compensator must meet the requirements in the design documents and shall be pre-tensioned or compressed according to relevant requirements.
Check quantity:full check.
Check method:observe and check the pre-tensioning or pre-compressing records.
5.10.4 The pressure test for pipe shall meet the requirements in the design documents.And it shall meet the requirements in current national standard GB 50235 Code for Construction and Aacceptance of Industrial Metallic Piping.
Check quantity:full check.
Check method:check the pressure test records.
Ⅱ General Items
5.10.5 The packing（backing）seal between flange faces shall meet the requirement in the design documents and they shall be closely contacted.The installation of flange and connecting bolt shall meet the requirements in current national standard GB 50235 Code for Construction and Acceptance of Industrial Metallic Piping.
Check quantity:20% random check for flanges on pipes of same type，and at least 1 pair of flanges.
Check method:check with a steel rule，trial fastening by a wrench and take visual check.
5.10.6 The flange，welding seam and connecting piece shall be arranged for easy repair and maintenance，the clear distance between circumferential welding seam and support shall not be less than 50mm.
Check quantity:full check.
Check method:observe and check with steel rule.
5.10.7 The gradient and sloping direction of pipe shall meet the requirements in the design documents.
Check quantity:random check for 3 points on every 100m of straight section，2 points for straight section less than 100.
Check method:check the installation quality record or check with level gauge.
5.10.8 The allowable installation deviation of brazed steel pipe shall meet the requirements in Table 5.10.8.
Check quantity:random check for 3 points on every 100m of straight section，2 points for straight section less than 100.
Check method:see Table 5.10.8.
Table 5.10.8 Allowable installation deviation of large-diameter coil-welded steel pipe（mm）
Note:H refers to support length；L refers to effective length of vertical pipe.
5.10.9 The allowable installation deviation of bustle pipe shall meet the requirements in Table 5.10.9.
Check quantity:full check.
Check method:see Table 5.10.9.
Table 5.10.9 Allowable installation deviation of large-diameter coil-welded steel pipe（mm）
5.10.10 The allowable installation deviation of riser and downcomer for blast-furnace gas shall meet the requirements in Table 5.10.10.
Check quantity:full check.
Check method:see Table 5.10.10.
Table 5.10.10 Allowable installation deviation of riser and downcomer（mm）
5.10.11 The allowable installation deviation of flange between pipe and valve shall meet the requirements in Table 5.10.11.
Check quantity:10% random check for valves.
Check method:see Table 5.10.11.
Table 5.10.11 Allowable installation deviation of flange between pipe and Valve（mm）
Note:D refers to flange diameter，d refers to pitch diameter of bolt hole on flange.
Fig.5.10.11 Bolt hole positioning on flange face
1-Valve flange 2-Hung centerline and plumb