Match more than nominal size
Confirm pipe dimensions and service together with flange standard, class, facing, drilling and material. Matching holes do not prove that two components have the same rating or sealing geometry.
Create one verified list covering line number, flange, gasket, bolting and weld preparation. ASME PCC-1 treats inspection, alignment, gasket installation and controlled tightening as one assembly process.
Inspect the sealing faces
Remove old gasket, paint, oil, rust and weld spatter without damaging the specified surface finish. Do not conceal grooves, distortion or corrosion with a thicker gasket or extra torque.
Check holes, threads, washers and nut-bearing surfaces. ASME guidance recommends that gaskets are not reused; appearance alone is not an acceptance criterion.
Align without pulling the pipe in
Check centreline, parallelism, rotation and gap before inserting bolts. Drawing a misaligned line together with the bolts can load the pipe, welds and equipment nozzles.
Adjust supports and temporary restraints so the faces meet naturally. Use the limits in the project, equipment documentation and applicable standard rather than visual judgement.
Select and centre the specified gasket
Gasket material and geometry must suit fluid, design temperature and pressure, facing and required compression. Flat-face, raised-face and ring-type joints are not interchangeable.
Use a new, clean and undamaged gasket, centred without unapproved grease, tape or adhesive. Reopen the joint if the gasket moves during bolt insertion.
Control the bolting system
Use the specified stud or bolt diameter, material, nuts and washers. Friction and lubrication strongly affect the conversion of torque into bolt load.
Verify clean thread engagement and use the approved lubricant and calibrated tool. A generic internet torque table cannot replace the value developed for the actual flange, gasket and bolting combination.
Tighten in staged cross-pattern passes
Hand-tighten all nuts, check the gap, then approach the target through numbered cross-pattern passes. Taking one bolt directly to final torque can compress the gasket unevenly.
Garlock instructs multiple passes with a calibrated torque wrench, followed by a final consecutive pass. Record the sequence and readings; never improvise tightening on a pressurised joint.
Test and commission under control
Record components, gasket, tool and calibration. Pressure-test only to an approved plan with the correct medium, exclusion zone and authorised personnel.
Raise pressure gradually and keep people away from the flange separation plane. Depressurise before investigating leakage, and retighten after start-up only when the approved procedure specifically requires it.