Precautions for High-temperature Pipeline Flange Installation

The installation of flanges on high-temperature pipelines is more stringent than ordinary pipelines.Improper operation will easily cause flange deformation,gasket aging,bolt loosening and medium leakage.The key installation notes are as follows:

Strictly Select High-temperature Resistant Materials

Choose high-temperature flanges,alloy steel bolts and special high-temperature gaskets that match the design temperature.Ordinary carbon steel gaskets and common rubber sealing parts are prohibited,as they will soften,deform or fail rapidly under long-term high temperature.

Control Flange Parallelism and Alignment

Ensure two connecting flanges are kept parallel and concentric.Avoid forced docking,bending stress and misalignment.High temperature will expand the pipeline,and residual stress will accelerate flange cracking and sealing surface damage.

Standardize Bolt Tightening Process

Adopt diagonal and segmented cross tightening.Complete pre-tightening and final tightening in multiple steps to ensure uniform stress on the flange face.Excessive single-side force will lead to local warping and permanent deformation at high temperature.

Implement Hot Retightening

After the pipeline is heated to the working temperature and runs for a period of time,perform secondary hot retightening on all bolts.Thermal expansion will reduce bolt preload,which is the main cause of high-temperature flange leakage.

Avoid Mixed Installation of Accessories

Do not use irregular thin gaskets,double gaskets or cushion gaskets.Keep the sealing surface clean and intact without scratches,corrosion or sundries,to maintain stable sealing performance under continuous high temperature.

Reserve Thermal Expansion Margin

Reasonably reserve expansion and contraction space for high-temperature pipes.Prevent flange joints from bearing additional tensile or extrusion stress caused by thermal expansion and cold contraction.

Strengthen Anti-corrosion and Heat Insulation

Wrap heat insulation materials outside the flange connection to reduce temperature difference stress.Do a good job in high-temperature anti-corrosion treatment for bolts and exposed metal parts to avoid oxidation and rust failure.