Gas Permeation
MERL has developed a unique high pressure (10,000 psi;
690 bar) gas permeation methodology for elastomers employed in harsh
offshore
oil and gas applications.
This has been extended to encompass thermoplastics
and thermosets. Lower pressure tests (<10 psi) can also be undertaken.
The test allows measurement of inherent material properties such as
the coefficients of permeation, diffusion and solubility, at temperatures
up to 250°C.
Explosive Decompression
By utilizing these coefficients in combination
with material mechanical properties such as tear strength and modulus,
MERL can
estimate the likelihood of a material's susceptibility to ED
damage. This is critical for elastomers (less so for thermoplastics)
in high pressure gas applications where there is a chance that the
external pressure can suddenly decrease. As the gas comes out
of solution
in the
material,
it may cause irreversible damage if relevant mechanical properties
are insufficiently high; this can lead to leakage in a sealing application.
MERL has dedicated equipment that can directly evaluate material
ED resistance by repeated pressure cycling. Tests can be performed
to:
NORSOK M710
API 17K and 17J
NACE TM0192 and TM0297
TOTALELFFINA SP TCS 142 Appendix H
Corporate standards or dedicated tests can be developed to replicate
particular service conditions.
To assist with visualisation and determination of non-equilibrium
gas diffusion situations, MERL has access to Finite Element Analysis
code which also allows modelling of complex sample geometries. The
code has been used to investigate the effect of external metallic
pressure windings on the permeation of gas through flexible thermoplastic
pipe, and also to study the influence of thermal gradients on diffusion.
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