double block and bleed plug valve Description
Double-block and bleed plug valve (DBB Valve) is a special valve that integrates double-blocking, bleed and sealing detection functions. It is mainly used for safety control of high-risk media pipelines such as oil and gas storage and transportation, chemical industry, etc. Its core functions include:
Double-blocking: Two independent sealing pairs (soft/hard seals) cut off the medium at the same time to achieve double isolation protection;
Relief: After closing the main valve, the bleed valve can discharge the residual medium in the valve cavity to verify the sealing and prevent abnormal pressure increase;
Fire safety: When the soft seal fails, the metal hard seal can still maintain the seal, meeting the API 607/6FA fire protection standard.
Structural composition and technical characteristics
Main structure:
Valve body and plug: Made of cast steel, stainless steel (304/316L) or hard alloy, with reduced flow path design to reduce costs;
Sealing system:
Soft seal: Fluororubber or PTFE molded, zero leakage at room temperature (leakage level VI);
Hard seal: Valve body inner cavity is hard chrome plated or surfacing Stellite alloy, resistant to high temperature and high pressure (-29~500℃).
Drive mode:
Manual (worm gear), pneumatic or electric drive, supports 90° rotation + linear motion composite operation;
Equipped with synchronous indicator, real-time display of valve switch status.
Relief device:
Independent relief valve or middle cavity pressure relief structure, relief pressure range 0.6-4.0MPa.
double block and bleed plug valve Specification
1. Pressure range: CLASS 150Lb~900Lb
2. Nominal diameter: NPS 2~36″
3. Body material: A105､LF2､F304､F316､F304L､F316L､F51,WCB､LCB､WCC､CF8､CF8M､CF3､CF3M､A890 4A etc.
4. End connection: RF RTJ BW
5. Drive device: Lever, Gear box, Electric, Pneumatic, Hydraulic device, Pneumatic-hydraulic device.
double block and bleed plug valve
Advantages
Safety redundancy: The double seal design reduces the risk of single-point failure, and the probability of leakage is reduced by more than 90% compared with ordinary valves;
Online maintenance: Seals (such as slides and valve seats) can be replaced without disassembling the valve, and pressure operation is supported;
Long life: The sealing surface has no friction and wear, and the service life is more than 28,000 times (certified by Hefei General Machinery Research Institute);
Economical: After localization, the cost is only 1/3-1/4 of imported products, and the price of a single valve has dropped from hundreds of thousands of yuan to 100,000-200,000 yuan.
Applications
Oil and gas storage and transportation: Crude oil storage tank import and export pipelines to prevent mixing of different oil products and metering errors;
Chemical process: Safe isolation of acid-base medium alternating transmission pipelines;
Gas system: Emergency shut-off and pressure relief of the high-pressure pipeline network of LNG receiving stations.
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