This final rule reduces the time and cost of hydrostatic testing in light of studies which show that the currently required 24-hour hydrostatic hold period is unnecessary. A two part test is'prescribed for hydrostatically testing liquid pipelines: A strength test of at least 4 hours' duration at a pressure equal to 125 percent or more of the maximum operating pressure is prescribed for all hazardous liquid pipelines subject to Part 195; additionally, a leak test for four hours or more at a pressure equal to 110 percent or more of the maximum operating pressure is prescribed for those pipelines which are not visually inspected for leakage while under, the strength test.