OFFSHORE CHINA PIPELINE GETS HEAVY COATING

Pipe coating for the 552-mile, 28 and 14-in. Yacheng 13 gas and condensate pipeline project has begun in Zhanjiang, China. The work is being done by Zhanjiang Zhonghai Bredero Price Coaters Inc., a joint venture of Bredero Price International B.V. and Nanhai West Oil Corp., both of Singapore. The joint venture was formed with the assistance of Hai Feng Marine, Singapore. Mobilization for coating application began Apr. 1 with coating trials set for 14 weeks later and full coated-pipe

Oct. 4, 1993

3 min read

The joint venture was formed with the assistance of Hai Feng Marine, Singapore. Mobilization for coating application began Apr. 1 with coating trials set for 14 weeks later and full coated-pipe production beginning Aug. 1.

The line is scheduled for installation in the South China Sea beginning Dec. 1 by European Marine Contractors Ltd. (EMC), London, and Saipem SpA of Italy using EMC's Semac 1 semisubmersible lay vessel. Project completion targets summer of next year (OGJ May 3, p. 41).

THE PROJECT

The Yacheng 13 pipeline project will move 336 MMscfd to Hong Kong for Castle Peak Power Co. The pipeline will consist of approximately 788 km (490 miles) of 28 in. and 100 km (62 miles) of 14-in. pipe. The Yacheng gas field lies in 300 ft of water approximately 100 km south of Hainan Island.

The pipeline is owned by a consortium consisting of Nan Hai West Oil Corp., Arco International, and Kuwait Foreign Petroleum Exploration Co. Arco China Inc. will be operator.

The gas, with a CO2 concentration of 8%, will be separated and treated on the platform with condensate piped ashore to Sanya City on Hainan Island via the 14-in. line.

The treated gas will be transported via the 28-in. pipeline from the platform to Hong Kong. This will be the second longest offshore pipeline ever coated or constructed, behind Zeepipe in the North Sea.

The pipe line has been designed with a 50-year life expectancy. Pipe specifications are the following:

14-in. ERW API 5LX x 8.7 and 14.3 mm (0.348 and 0.572-in.) W.T.; and,
028-in. DSAW API 5LX x 15.88 and 19.05 mm (0.635 and 0.762-in.) W.T.

Pipe is specified for sour service and supplied by several Japanese mills including Nippon, Kawasaki, Sumitomo, and NKK.

THE COATING

In March, Bredero Price International was awarded the coating contract.

With the lengthy life expectancy, specifications for the corrosion and weight coatings are among the most stringent ever, according to Bredero Price.

The coating will consist of 6 mm of coal-tar enamel with two fiber glass inner wraps and one fiber glass-reinforced outer wrap. The inner wrap is manufactured by Balzaretti Co., Milan; the outer wrap, by Metrotect, West Yorkshire, U.K. The coal-tar enamel is manufactured by Metrotect.

The Hevicote concrete coating will be 190 lb/cu ft, and on site welded wire cages will be used to provide maximum reinforcing strength (Fig. 1). The concrete mix strength is 6,000 psi.

Because of the coating-requirement stringencies, Bredero Price has installed a precise "batch plant" mixing facility to ensure that the exact percentages of the required concrete materials are properly measured and mixed before being applied to the pipe (Fig. 2).

A pipe tracking and weighing system is completely computerized,

Because of the short time frame allowed for the coating works (11 months), Bredero Price has designed a new concept for the application of Hevicote concrete.

Through use of a pipe "buggy" system, the pipe will move continuously through the system without interruption in the coating operation.