API Plan 53B

• As with all double mechanical seals using a higher barrier fluid pressure compared to the process fluid pressurise, process media quality can deteriorate due to barrier fluid contamination. In process media sensitive applications where barrier fluid contamination is not permitted, dry running sealing technology is employed, where the barrier media is gas.

• Used in applications where direct gas pressurisation (as found in Plan 53A systems) is not acceptable.
• Plan 53B systems are high-end systems which are typically used in hazardous applications where no leakage to atmosphere can be tolerated.
• Typical applications of Plan 53B systems are found in the Oil and Gas industry, which process toxic, environmentally dangerous and inflammable media.
• Plan 53B systems are excellent for dirty, abrasive and slurry applications, where the process media is not suitable to be used for the fluid film between the counter-rotational seal faces.
• Plan 53B systems are also used in polymerizing products.

• The bladder accumulator is typically manufactured from a flexible, elastomeric material. Periodic inspection the bladder accumulator is therefore mandatory. Inspect for wear and deterioation of the bladder and/or surface finish contact/wear of the internal surfaces of the seal support system.
• Recharge the bladder to x0.9 the working pressure.
• As with any pipework system, always vent the Plan 53B system properly before equipment start up.
• As with all pressurised double seals, always check the barrier fluid compatibility with process media. There will always be some leakage of barrier fluid into the process media.
• Significant environmental temperature changes and heat load can cause fluctuations on the system pressure.

For further reading on API Plan 53B seals and systems, please click the following links to related Technical Blogs;

• Why we must remove heat from mechanical seal faces