4.4　Inspection of Pipe Accessories

4.4.1　The screw thread of bolts and nuts shall be complete and have no defects such as scratches or burrs.Bolts and nuts shall be in well fit and have no looseness or jam fault.The specification of bolts and nuts shall meet the requirements of GB/T 9125 Fasteners for Pipe Flange Joints.The tolerance of bolts and nuts shall meet the requirements of the screw thread precision grade 6H in GB/T 197 General Purpose Metric Screw Threads-Tolerances.

4.4.2　Alloy steel bolts at the working temperature above 400℃and the specification no less than M32 shall be numbered one by one and their hardness shall be tested.The unqualified bolt shall not be used.

4.4.3　Each part of pipe supports and hangers shall meet the following requirements.

1　The type and material of pipe supports and hangers shall meet the requirements of the design drawing.

2　The welds shall have no lack of weld or incomplete weld.The surface of welds and heat affected zone shall have no defects such as cracks,obvious undercuts or deformation.

3　The diameter and the length of bars shall meet the requirements of the design drawings and have no rusts,bending or scratches on the surface.

4　The rolling and sliding working surface of supports shall be flat,smooth and non-jam situation.

5　Each part shall adopt mechanical processing and rust prevention.

6　Springs shall meet the following requirements.

1)The certificate of compliance and quality certificates from the manufacturer shall be provided.The type and size shall meet the requirements of the design drawings.

2)The surface shall have no defects such as cracks,deformation,rusts or scratches.

7　Spring assembly shall be locked at the pin according to the design requirement.The indicator scale shall be clear,and the pointer shall be intact.