Installing grooved pipe fittings requires strict adherence to standards and control over the entire process-from preliminary preparation to final acceptance-to prevent common issues such as leakage and deformation. Specific considerations are as follows:
Pre-installation Preparation
Material Verification: All pipes, fittings, and gaskets must come with manufacturer certificates of conformity. They must be free of surface defects like cracks, rust, or blowholes, and their specifications must perfectly match the piping system.
Tool Specifications: Specialized tools (such as roll groovers and pipe cutters) must be calibrated beforehand. Use only neutral lubricants like soapy water; oil-based lubricants are strictly prohibited as they can corrode the gaskets.
Support/Hanger Pre-installation: Install pipe supports and hangers according to design requirements prior to pipe installation; do not rely on the couplings alone to bear the weight of the pipe.
Roll Grooving Stage
Pipe End Pre-treatment:After cutting the steel pipe, grind away any burrs and ensure the cut end is perpendicular to the pipe's central axis. Oxy-acetylene cutting is strictly prohibited.
Groove Dimension Control: Use a vernier caliper to verify that groove depth and width meet national standards. Apply downward pressure slowly and evenly to prevent pipe end deformation (such as flaring).
Processing Protection: Rotate the pipe one full turn before grooving to ensure there is no misalignment and that the groove depth is uniform. After processing, clean away any residual galvanizing material from the pipe end and apply anti-corrosion treatment.
Fitting Connection and Installation Stage
Installation Sequence: Follow the principle of installing large-diameter mains and risers first, followed by small-diameter branch pipes; do not skip steps or install in a fragmented manner.
Gasket Installation: Ensure the gasket fits with uniform tension around the circumference. If wrinkling or bulging occurs, replace it immediately; do not force the coupling shut.
Coupling Tightening Requirements: Ensure the coupling's raised edges seat fully into the grooves. When tightening bolts, alternate symmetrically and apply force gradually and evenly, ensuring the final torque is within the 25–30 N·m range.
Special Fitting Installation: For mechanical crosses, ensure the openings on both sides are concentric; for mechanical tees, ensure the fitting aligns concentrically with the hole to prevent gasket rupture.