One technological problem of rubber O-rings used in hydrogen equipment is the occurrence of internal fractures called blisters caused by gas decompression. The use of damaged rubber leads to the decrease in sealability. Our previous study clarified influencing factors on such rubber fractures by quality engineering, based on durability tests with a few hundred pressure cycles. However, the seal durability should be evaluated under the long-term pressure cycle condition which reproduces a realistic pressure environment. This study determined a realistic pressure cycle condition influencing the fracture and sealability by using a developed durability tester. Under the condition, precise durability tests at 5,500 cycles were performed. The results showed that no leakage due to fatal fractures occurred at the condition.

Using computer software 1œSolid Works1 for generate the geometric form of the seal's rings and 1œANSYS-9 WORKBENCH1 program for the FEM analysis to calculate mechanical stresses and thermal loadings of a mechanical seals as a part of the centrifugal pumps working in an oil refinery. The goal of this analysis is to improve the design of the seal. The analysis was performed for the mechanical seals of the 100P3A and 100P3R pumps of an oil refinery. Two 1œscenarios1 was considered; each them is an 1œengineering1 simulation. To define the simulations we considered as known: the type of material and the material properties; the behavior of the contact surface of rings; the types and the magnitude of the loadings on the ring. As a variable are considered the geometric shape of the rings and loadings. Type of the material of sliding rings: silicon carbide/graphite. For the Scenario No.1, the two sliding rings of the mechanical packing resist to compression stress in the normal running conditions (work in the presence of auxiliary liquid). The two sliding rings resists even in the damage conditions (in the absence of the auxiliary liquid), like we can see in the Scenario No.2. The equivalent stress (Von Misses) had a maximum value in the silicon carbide ring for the both scenarios. The maximum strain (deformation) is in the graphite ring, in the both scenarios and it is 1,3 times greater in the scenario No. 2 (damage running conditions).