Fire Protection on the Beryl A Platform
Authors: Slye O.M. 
Published: December 2007

This paper describes the fire protection systems of a large offshore platform in the North Sea. The Beryl A platform had several unique risk platform in the North Sea. The Beryl A platform had several unique risk factors, including size, high production rates, and platform construction, that required careful analysis. Fire protection solutions and safe operation of the facility also are discussed.

Introduction

With more exploration and production in the North Sea, new engineering techniques are required to provide protection from fire and explosion. The severe risk of protection from fire and explosion. The severe risk of fire associated with North Sea platforms is illustrated by the Beryl A platform, compared in Fig. I with some well known landmarks. Located more than 200 miles offshore in 392 ft of water, the platform has a concrete base support topped with a steel deck structure and quarters. Sixteen of the 19 base cylinders are used for crude oil storage and have a capacity of 950,000 bbl. These cylinders extend 150 ft above the sea floor. The remaining three cylinders are used as main support towers and extend an additional 300 ft to support the steel deck structure. The steel deck rises 100 ft above low average tide. The steel deck structure is 197 x 230 ft with two levels, each about 1 acre in area and spaced 33 ft apart. The enclosed compartmental steel structure houses equipment and facilities for production, drilling, recompression, utilities, and life support systems.Over-all weight of the structure is 350,000 tons, which keeps the structure in place, anchored by steel dowels more than 6 ft across and projecting into the sea bed 16 ft below the bottom of the structure. The platform eventually will produce up to 100,000 B/D. Crude oil will be pumped from the platform to a single-point mooring pumped from the platform to a single-point mooring structure and then to specially designed bow-loading tankers. Fig. 2 shows the platform in its towing position and illustrates the size of the structure.

Design Objective

Fire protection and safety provisions incorporated in the platform provide maximum protection against risks of platform provide maximum protection against risks of fire and limit the exposure of employees to fire and explosion.Fire safety design includes several interrelated fire safety systems, including detection systems for hazardous accumulations of flammable gases, fire detection, smoke detection in areas with potential for smoldering fires (such as quarters and electrical equipment areas), fire extinguishing systems, fireproofing of structural elements, and fire walls between compartments. A major element of the fire system design is the combustible gas detection system. These devices provide warning of hazardous conditions well ahead of a potential fire.

Combustible Gas Detection

The combustible gas detection system has a network of sensors located strategically throughout each compartment, signaling in the control room. The sensors are sensitive to hydrocarbon vapors and will be calibrated to signal an alarm when vapor concentration reaches 20% of the lower explosive limit (LEL). The LEL is that point where flammable vapors mixed with air can be ignited. At 60% of the LEL, the detection systems will signal an alarm and also begin interlocking with other fire safety systems. The function of the interlock varies, depending on occupancy of the compartment where flammable vapors are detected, and may include fire extinguishing or deactivating systems, and/or process shutdown.

JPT

P. 1377