LARGEST TAIWAN SPM TERMINAL INSTALLED

Feb. 17, 1992
A. R. Schultz Intec Engineering Inc. Houston Chinese Petroleum Corp. (CPC) last year installed and commissioned Taiwan's largest single-point mooring (SPM) terminal. This, the third of four planned SPM terminals, is unloading 100,000-300,000 dwt crude-oil tankers 5 miles offshore Kaohsiung, Taiwan, on the southwest coast of the Republic of China (Fig. 1). Construction on the fourth SPM terminal, for unloading naphtha and diesel gas oil from 20,000-100,000 dwt tankers, began late last year.
A. R. Schultz
Intec Engineering Inc.
Houston

Chinese Petroleum Corp. (CPC) last year installed and commissioned Taiwan's largest single-point mooring (SPM) terminal.

This, the third of four planned SPM terminals, is unloading 100,000-300,000 dwt crude-oil tankers 5 miles offshore Kaohsiung, Taiwan, on the southwest coast of the Republic of China (Fig. 1).

Construction on the fourth SPM terminal, for unloading naphtha and diesel gas oil from 20,000-100,000 dwt tankers, began late last year.

The third terminal consists of a catenary anchor leg mooring (CALM) system, a 56-in. (1,422 mm) OD crude-oil pipeline and a 16-in. (406 mm) OD fuel-oil pipeline. The subsea pipelines extend from the CALM installed in a water depth of 118 ft to an existing shore tank farm tie-in valve station.

Construction began in October 1990 and was completed in May 1991. Because of typhoons in the Strait of Taiwan, which can produce maximum 1-min sustained wind speeds of 145 knots (75 m/sec) and maximum wave heights of 62 ft (19 in), offshore construction is generally scheduled to be completed before the start of typhoon season, which extends from the beginning of through the end of September.

This third and largest SPM terminal installed by CPC supplies crude oil to the Kaohsiung refinery. The first and second SPMs and associated pipelines, designed for unloading 100,000 and 200,000 dwt tankers, were installed in 1969 and 1971.

SPM SYSTEM

The SPM terminal utilizes a dual-product CALM system simultaneously to unload crude-oil tankers at 75,000 bbl/hr (12,000 cu m/hr) through the 56-in. pipeline and load fuel oil at 1,260 bbl/hr (200 cu m/hr) through the 16-in. pipeline.

The terminal facilities are designed for future crude-oil unloading rates approaching 94,000 bbl/hr (15,000 cu m/hr).

Designed and supplied by Sofec Inc., Houston, the CALM system consists of a 41 ft diameter x 19 ft mooring buoy and a rotating turntable equipped with a dual product fluid swivel and piping system. This system consists of dual 24-in. (610 mm) OD piping for crude-oil transfer and 12-in. (305 mm) OD piping for fuel-oil transfer (Fig. 2).

The buoy is held on location by the six 4.5-in. diameter Grade 3 stud link anchor chains, extending approximately 1,170 ft (357 m) from the buoy chain stoppers to 18-ton Stevpris high holding-capacity anchors embedded in the sea floor.

Mooring the tanker to the rotating turntable mounted on the buoy hull uses dual 16 in. (circumference) x 200 ft (61 m) long grommet double-braided nylon mooring hawser assemblies, including reusable thimbles, lace-on-floats, 3-in. diameter chafing chain, chain support buoy, and pick-up line assembly.

The floating hose system, which connects the tanker manifold to the buoy turntable piping, consists of dual 24-in. hose strings for crude-oil transfer and one 12-in. hose string for fuel-oil transfer. The floating hose strings are approximately 980 ft long.

The underbuoy or submarine hose system which extends from the buoy center-well piping to the pipeline-end manifold (PLEM) has the same number and diameter hose strings as the floating hose strings and utilizes a steep-wave hose configuration with a single-hose support buoy.

The 40 ft (12 m) x 30 ft (9 in) PLEM, anchored to the seafloor by four 36-in. (914 mm) diameter tubular steel piles, utilizes a sliding piping assembly mounted on a support frame to accommodate pipeline thermal expansion.

The PLEM piping includes two 24-in. pipe spools branching off the 56-in. PLEM header and one 16-in. diameter pipe spool (Fig. 3). Each piping spool includes a manually operated ball valve and check valve.

The SPM and PLEM, designed by Sofec, were fabricated by China Shipbuilding Corp. (CSBC) at its Kaohsiung, Taiwan, facility.

PIPELINE SYSTEM

The 56-in. OD x 0.750-in. W.T. and 16-in. OD x 0.469-in. W.T. Grade X-60 line pipe were manufactured according to API Specification 5L, modified to include hydrogen-cracking sensitivity testing requirements, by Far East Machinery Co. (Femco), Chiayi, Taiwan.

Femco also manufactured the 57.25 in. (1,454 mm) OD x 1.375-in. W.T. x 4.6 ft (1.4 m) long buckle arrestors welded into the middle of individual pipe joints at the pipe mill. The pipe joints with buckle arrestors were installed at 500 ft (152 m) intervals for water deeper than 96 ft (29 m).

The 56-in. and 16-in. lines were externally coated with a 120 mil (3 mm) thick machine-applied, spirally extruded, polyethylene (PE) corrosion-protective coating at the Femco pipe mill.

To weight coat the line pipe, Italian pipe coating concern Socotherm utilized a portable concrete weight-coating machine imported to Taiwan and set up near Kaohsiung (Fig. 4). The 190 lb/cu ft density steel-wire-reinforced concrete was applied by the impingement method to a thickness of 1 in. for the 16-in. pipeline and 5.75 in. for the 56-in. pipeline, except for the shallow water portion of the pipeline which has a thickness of 6.5 in..

For the 56-in. pipe, the concrete was reinforced with three separated spiral-applied layers of 12.5 x 14 gauge, flash-welded, galvanized steel wire mesh. A single layer of wire mesh reinforcement was utilized for the 16-in. pipe.

Galvalum III bracelet-type anodes, manufactured in Singapore, were attached to line pipe joints before the application of concrete weight coating.

Anodes were spaced at 1,000 ft (305 m) intervals on the 56-in. pipeline and at 500 ft (152 m) intervals on the 16-in. pipeline.

PIPELINE INSTALLATION

After international tender, installation of the subsea pipelines and CALM system was awarded to Nippon Steel Corp. (NSC) which utilized the Kuroshio II combination derrick and centerslot lay barge.

The Kuroshio II is a 460 ft (140 m) x 112 ft (39 m) x 31 ft (9.5 m) combination derrick and pipelay barge with five welding stations, one X-ray station, one field-joint coating station, and six 50-ton capacity pipeline lifting davits.

The barge is equipped with two Western Gear LPT 100-kip, track-type tensioners, capable of laying up to 60-in. line pipe and with a revolving derrick crane rated for 725 tons at 90 ft radius with a 230 ft boom length.

The barge has a 10-point mooring system consisting of 10 single drum winches, each having 5,900 ft of 2.5-in. diameter wire rope and a 15-ton anchor suitable for operation in 660 ft of water.

NSC was also responsible for the onshore tie-in work at the refinery tank farm. This included reinforced concrete valve boxes, two major road crossings performed by hydraulically jacking large diameter prestressed concrete culvert sections beneath the roadways, and installing approximately 1,640 ft of 56, 16, and 34-in. pipelines in a sheet-pile-retained excavation.

The onshore end of the 56-in. pipeline terminated with a manifold section containing two 36-in. diameter extrusions for connection to an existing 42-in. (1,066 mm) OD pipeline previously constructed with two 36-in. diameter side-mounted flanges for future tie-ins.

Two pipeline tie-in spools, each equipped with an elastomeric coupling (flexible joint) designed for 10 lateral deflection at each end were installed to accommodate pipeline thermal expansion at the onshore tie-in point.

Two onshore sections of 34-in. pipeline were installed in advance of the fourth SPM project to reduce future onshore disruptions of ongoing civil construction projects by others.

Installation of the 16-in. pipeline began on Jan. 28, 1991, and was completed on Feb. 6. That was followed by installation of the 56-in. pipeline, which was completed on Mar. 15 at an average rate of 25 joints/day utilizing an internal line up clamp and manual welding.

A two-section rigid truss-type stinger with an overall length of 252 ft was used to lay the 56-in. pipeline without the use of the tensioner system. The 16-in. pipeline utilized the tensioner system but did not require use of the stinger.

To initiate the offshore pipelay, the Kuroshio II was anchored approximately 500 ft from the shoreline. As pipe joints were welded, X-rayed, and coated on the lay barge, the pipeline was pulled from the barge to the onshore tie-in point through a reaction sleeve by a 90-ton abandonment and recovery winch (ARW) on the lay-barge.

Temporary buoyancy was attached to the pipeline during the pulling operation to reduce the submerged pipe weight. All welds were X-rayed with an isotope-controlled, OIS-supplied internal X-ray crawler. The film was processed by a Kodak RP X-Omat automatic processor and interpreted by inspectors qualified to Level II as defined by the American Society for Nondestructive Testing.

Servi-Wrap M30B corrosion protective field-joint coating was applied over the weld area, and the field joint was filled with a high density aggregate-filled, two-component polyurethane elastomer.

Pipeline burial began on Feb. 1 and used a separate bury barge equipped with a mechanical trenching system.

It was completed on Mar. 27 (Fig. 5). The top of the 56-in. pipeline was lowered 3.3 ft below the seafloor in a single pass.

Installation of the PLEM, PLEM piling, SPM anchors and anchor chains, mooring buoy underbuoy and floating hoses, and mooring hawsers began on Mar. 14 and was completed on Apr. 10, 1991 (Fig. 6). Hydrostatic testing of the pipelines and SPM system was completed during the same time period.

COMMISSIONING

After completion of the onshore tie-in at the existing tank farm, the completed offshore terminal was commissioned on May 10, 1991.

Intec Engineering Inc., Houston, was responsible for the engineering and construction management including offshore hydrographic and geotechnical survey, detailed pipeline design, drawings and specifications, SPM performance specification, preparation of sample contract and tender documents, technical bid evaluation, SPM detailed design review, SPM component inspection, pipeline and SPM installation inspection, and terminal commissioning.

Intec has been contracted by CPC to provide the same services for the Talinpu SPM No. 4 project.

As of Feb. 1, line pipe for this fourth SPM was being concrete weight-coated in Taiwan by Socotherm. That SPM, also designed by Sofec, is under construction at China Shipbuilding. IPCO Marine, Singapore, the prime contractor, has begun the onshore tie-in preparation.

Construction of the offshore pipelines will begin next month with installation of the SPM set for June.

ACKNOWLEDGMENT

The author expresses his appreciation to Chinese Petroleum Corp. for permission to publish this article.

Copyright 1992 Oil & Gas Journal. All Rights Reserved.