mstengel
Mechanical
- Jul 1, 2015
- 1
Dear specialists out there,
We're supplying big liquid ring compressors for a refinery project. Customer insists on gas leak test, which is optional scope of API 681 (par. 4.3.1.1 & 4.3.4). In similar projects this optional test was never requested for this type of compressor or customers accepted execution with 1 barG instead of discharge pressure. The background for reduced pressure: Proper bubble forming won't happen at higher pressures (when the gas just streams out). But here test shall be conducted at full discharge pressue. This leads to some questions to those who done such tests.
(1) Which safe method of leak supervision and localisation is reommended? Aspect of safety: our company safety policies contain some reasonable limitations for working with closed volume of pressurized gas due to stored energy. Presence of personell at machine under testing conditions will not be possible. This leads to idea of testing under water and observation for gas bubble under water. Any alternatives?
(2) API says that "end seals" shall be installed. This term is not defined. Does this refer to mechanical shaft seals? I'm wondering, because mechanical seal might be very likely leak path, if not rotating and not properly connected to seal system (with overpressure etc.). And competitors are offering such test for casing only (impeller and shaft seals removed). How do you conducting such test? Complety assembled compressor? If yes, how are mechanical seals handled? If not, how can this be brought in line with API requirement?
Some insights in common practice would be appriciated.
We're supplying big liquid ring compressors for a refinery project. Customer insists on gas leak test, which is optional scope of API 681 (par. 4.3.1.1 & 4.3.4). In similar projects this optional test was never requested for this type of compressor or customers accepted execution with 1 barG instead of discharge pressure. The background for reduced pressure: Proper bubble forming won't happen at higher pressures (when the gas just streams out). But here test shall be conducted at full discharge pressue. This leads to some questions to those who done such tests.
(1) Which safe method of leak supervision and localisation is reommended? Aspect of safety: our company safety policies contain some reasonable limitations for working with closed volume of pressurized gas due to stored energy. Presence of personell at machine under testing conditions will not be possible. This leads to idea of testing under water and observation for gas bubble under water. Any alternatives?
(2) API says that "end seals" shall be installed. This term is not defined. Does this refer to mechanical shaft seals? I'm wondering, because mechanical seal might be very likely leak path, if not rotating and not properly connected to seal system (with overpressure etc.). And competitors are offering such test for casing only (impeller and shaft seals removed). How do you conducting such test? Complety assembled compressor? If yes, how are mechanical seals handled? If not, how can this be brought in line with API requirement?
Some insights in common practice would be appriciated.
