Pressure and method of sealing performance test

The sealing performance test is carried out after adjusting the adjustment pressure, and the inlet pressure of the safety valve is lowered and adjusted, so that the seal performance test is kept for one minute under the condition of sealing test pressure.

For a closed safety valve, install a leaky tube at the discharge outlet side of the safety valve, the inner diameter is 6 mm, the pipe outlet end face and the axis are perpendicular and keep smooth, placed in the open type water tank, the pipe end face is inserted under 12. 5 mm, and parallel to the water surface, with the outside in a completely airtight state (bonnet, drain hole, export, etc. should be closed). In the sealed test pressure state, check the number of bubbles per minute to indicate the leakage rate. For metal sealing surface valves, should not exceed the gb/t12243-2005 table 12 of the value, for non-metallic elastomeric material sealing surface valve, should not leak phenomenon (0 bubbles per minute).

For non-closed safety valve, in the sealed test pressure state with visual observation of the pressure gauge pointer drop or listen to check the gas leakage sound, in a minute did not find leakage, it is considered sealed qualified.

Safety Valve sealing performance test not less than three times, each test results must meet the requirements.

According to the "Pressure Vessel safety Technical supervision regulations", designpressure ≥ set pressure "seal test pressure" maximum working pressure, safety valve setting pressure of the maximum working pressure of 1. 05~1. 1 time times [2]. Special Inspection Center In view of the above provisions, the safety valve sealing test pressure to improve.

When the seal test pressure is lower than the maximum working pressure, the selection of seal test pressure must be higher than the maximum working pressure, so that it in the sealed test pressure state, to maintain a minute sealing performance test.

Grinding and repairing of sealing surface

The sealing surface is required to have higher strength and bear higher sealing pressure; have a certain impact toughness, can withstand the impact of rapid take-off back to the seat of the spool, a higher hardness, can withstand the medium scouring, can not rust, or quickly leakage, to withstand high temperature, the application of steam and other media, do not soften the temperature, to resist corrosion, withstand acid-base and other erosion. The sealing surface is under the high pressure condition operation, needs the very big preload, must use the hard material sealing surface, therefore, mostly uses the metal material to make the sealing surface. Seal surface is divided into plane seals, cone-type seals, ball-type seals, cone-type seals, ball-type sealing processing difficult, difficult to repair after damage, plane seal processing, maintenance convenience, the most widely used, when the sealing surface damage is not too serious or sealing performance requirements, grinding repair.

Grinding is in other metal processing methods can not meet the workpiece accuracy and surface roughness requirements, the use of precision machining methods, in measuring tools, equipment manufacturing and repair, widely used, usually manual operation. The material of the grinding table is well organized, the embedded abrasive has good performance, good stability and abrasion resistance, good lubricity, high efficiency, low cost, easy to process, do regular inspection and maintenance, such as the geometrical precision can not reach the requirements of timely correction, is the use of gray iron. On the grinding platform evenly coated with abrasives (abrasive and grinding fluid to reconcile the mixture), the seat, spool placed on the platform, under pressure to uniform, the pressure should be moderate. The pressure is big, the abrasive cutting quantity is big, the surface roughness is big, will cause the abrasive to crush, scratches the surface, reduces the grinding efficiency.

Grinding divided into rough, semi-fine, three steps, coarse grinding with 1~2 kg/cm2, the selection of corundum abrasive w40~20 differential, speed in every minute40~60 time; 5~1 kg/cm2, using corundum abrasive W10 differential, the speed of30~50 times per minute, with 0. 1~0. 5 kg/cm2, choose Corundum abrasive W2. 5 differential, speed 20~40 times per minute.