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Title: Repairing an offshore jacket structure proves cost effective

Abstract

During inclement weather in the southern North Sea, an off-shore supply boat collided with a 25-year-old gas production platform. The impact occurred just over 2 m (5.56 ft) from the lowest annual tide and was sufficient to buckle, then shear, one end of a horizontal bracing from the jacket leg and to cause further damage at a node joint. Inspection personnel performed an initial examination of the damage to the eight-leg jacket structure using rope access techniques (abseiling), which offered substantial cost saving over erecting scaffolding. A structural analysis confirmed the jacket's integrity was not impaired and loss of the horizontal bracing would not significantly affect the structure. The analysis also confirmed repair of the node weld cracks and of the sheared area on the leg should be performed as soon as practical. In the end, the repair went smoothly. The repair area was above the waterline, and the weather cooperated perfectly. The repairs were done using rope access techniques, and using austenitic electrodes reduced the possibility of HAZ hydrogen cracking. Nondestructive examination confirmed no cracking had been experienced and no other defects existed. Indeed, this methodology is considered extremely practical, cost effective and ideal for use on offshore structures--withmore » damage close to the waterline, and with the need to execute immediate repairs.« less

Authors:
;
Publication Date:
Research Org.:
Aberdeenshire (GB)
OSTI Identifier:
20030395
Alternate Identifier(s):
OSTI ID: 20030395
Resource Type:
Journal Article
Journal Name:
Welding Journal (Miami)
Additional Journal Information:
Journal Volume: 79; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 0043-2296
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; OFFSHORE PLATFORMS; DAMAGE; NATURAL GAS WELLS; REPAIR; WELDING; NONDESTRUCTIVE TESTING

Citation Formats

Still, J.R., and Blackwood, V. Repairing an offshore jacket structure proves cost effective. United States: N. p., 2000. Web.
Still, J.R., & Blackwood, V. Repairing an offshore jacket structure proves cost effective. United States.
Still, J.R., and Blackwood, V. Mon . "Repairing an offshore jacket structure proves cost effective". United States.
@article{osti_20030395,
title = {Repairing an offshore jacket structure proves cost effective},
author = {Still, J.R. and Blackwood, V.},
abstractNote = {During inclement weather in the southern North Sea, an off-shore supply boat collided with a 25-year-old gas production platform. The impact occurred just over 2 m (5.56 ft) from the lowest annual tide and was sufficient to buckle, then shear, one end of a horizontal bracing from the jacket leg and to cause further damage at a node joint. Inspection personnel performed an initial examination of the damage to the eight-leg jacket structure using rope access techniques (abseiling), which offered substantial cost saving over erecting scaffolding. A structural analysis confirmed the jacket's integrity was not impaired and loss of the horizontal bracing would not significantly affect the structure. The analysis also confirmed repair of the node weld cracks and of the sheared area on the leg should be performed as soon as practical. In the end, the repair went smoothly. The repair area was above the waterline, and the weather cooperated perfectly. The repairs were done using rope access techniques, and using austenitic electrodes reduced the possibility of HAZ hydrogen cracking. Nondestructive examination confirmed no cracking had been experienced and no other defects existed. Indeed, this methodology is considered extremely practical, cost effective and ideal for use on offshore structures--with damage close to the waterline, and with the need to execute immediate repairs.},
doi = {},
journal = {Welding Journal (Miami)},
issn = {0043-2296},
number = 5,
volume = 79,
place = {United States},
year = {2000},
month = {5}
}