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MSHA - Title 30 CFR
30 CFR § 7.104
Internal static pressure test.
(a) Test procedures. (1) Isolate and seal each segment of the intake system or exhaust system to allow pressurization.
(2) Internally pressurize each segment of the intake system or exhaust system to four times the maximum pressure observed in each segment during the tests of § 7.100, or 150 psig ± 5 psig, whichever is less. Maintain the pressure for a minimum of 10 seconds.
(3) Following the pressure hold, the pressure shall be removed and the pressurizing agent removed from the intake system or exhaust system.
(b) Acceptable performance. (1) The intake system or exhaust system, during pressurization, shall not exhibit--
(i) Leakage through welds and gasketed joints; or
(ii) Leakage other than along joints meeting the explosion-proof requirements of § 7.98(q).
(2) Following removal of the pressurizing agent, the intake system or exhaust system shall not exhibit any--
(i) Changes in fastening torque;
(ii) Visible cracks in welds;
(iii) Permanent deformation affecting the length or gap of any flame-arresting paths;
(iv) Stretched or bent fastenings;
(v) Damaged threads of parts affecting the explosion-proof integrity of the intake system or exhaust system; or
(vi) Permanent distortion of any planar surface of the diesel power package exceeding 0.04-inches/linear foot.