THE MAIN PIPE LINE

The main 30"-31" pipe line of both Aramco Gathering Facilities and Tapline has been tapered in wall thickness to reduce the initial cost and steel requirements to a minimum. The tapering is based on balanced pumping conditions with twelve pump stations at a maximum capacity Of 500,000 barrels per operating day. Initially, only six stations are being installed with a maximum capacity Of 300,000 barrels per operating day.

All of the 30"-31" pipe was manufactured by Consolidated Western Steel Corporation at Maywood, California, from plate supplied by the Geneva, Utah

mill. The plate was rolled into cylinders and longitudinally welded by the submerged arc process. The joints were then hydraulically expanded in giant dies to the exact outside diameters. This cold expansion process increased the yield point to a minimum Of 52,000 pounds per square inch.

In calculating the required pipe wall thickness, a maximum hoop stress of 65 per cent of nominal yield or 33,800 pounds per square inch was used. Based upon this limitation and a minimum wall thickness of 1/4", the following pipe distribution was installed:

About 60 per cent of the line is buried and 40 per cent above ground. The above-ground construction is of the restrained type and the line does not move due to temperature changes. The line is completely buried through Lebanon, Syria and Jordan, and was either buried or laid above ground in Saudi Arabia, depending on which was the most economical method.

Also, above-ground construction was used across corrosive subkhas (salt ftats) in the vicinity of Abqaiq, Qatif and Abu Hadriya.

All large gate valves in the system were manufactured by the WKM Company, Inc. and are of the doubleseating, ring-follower type. The 30" gate valves weigh about eleven tons each.