API Publ 342:1998 pdf download

API Publ 342:1998 pdf download.FUGITIVE EMISSIONS FROM EQUIPMENT LEAKS I: MONITORING MANUAL.
• Barrier fluids pressurized higher than the agitator cavity;
• A barrier fluid reservoir vented to a control device; and
• A pressure tight barrier fluid with a pressure alarm indicator.
In a hydraulic seal, an annular cup attached to the process vessel contains a liquid that contacts an inverted cup attached to the rotating agitator shaft. Although it is the simplest agitator shaft seal, the hydraulic seal is limited to low temperature/low pressure applications and can handle only vezy small pressure changes. A lip seal consists of a spring-loaded, non- lubricated elastomer element, and is limited in application to low-pressure, top-entering agitators.
Agitator seals can leak because of poor installation, aging, and deterioration of the seals themselves, thermal stress, and vibration.
2.1.2 Compressors
Compressors provide the force to transport gases through a process unit in much the same way that pumps transport liquids. There are centrifugal, reciprocating, and rotary compressors in use by industries affected by equipment leak regulations. The sealing mechanisms for compressors are similar to the packed and mechanical seals for agitators.
Connectors are used to join sections of piping and equipment. Connectors can be flanges, screwed or threaded connectors, union connectors, tubing connectors, caps, plugs, etc.
Flanges are bolted, gasket-sealed connectors. Flanges are normally used for pipes with diameters of 2.0 inches or greater. The primary causes of flange leakage are poor installation, aging and deterioration of the gasket, thermal stress and vibration. Flanges can also leak if improper gasket material is chosen.
The non-flange connectors (screwed, union, tubing, caps, plugs, etc.) typically are used to connect piping and equipment having diameters of 2.0 inches or less. Emissions from these connectors can occur as the sealant ages and eventually cracks. Leakage can also occur as the result of poor assembly or sealant application, or from thermal stress or vibration on the piping and fittings.
2.1.4 Open-ended Lines
Some valves are installed in a system so that they function with the downstream line open to the atmosphere. A faulty valve seat or incompletely closed valve on such an open-ended line would result in a leakage through the open end. In some locations open-ended lines are prohibited. A cap, plug, or blind flange used to control leaks from open-ended lines can also leak from improper installation and aging and deterioration of the gasket or threads. Because these leaks are similar to those found in connectors, a potentially open-ended line.