Developing a Generic Approach to HAZOPS Analysis of Offshore Production Facilities
Authors: Arnold K.E. , Sikes C.T. 
Published: October 2008

Recently HAZOP reviews have been receiving a great deal of attention as a possible method of improving process safety for offshore platforms in the Gulf of Mexico. This paper discusses the development of API RP 14C and demonstrates that 14C is the result of a generic HAZOP review of typical offshore production equipment. Historically, 14C has been effective in providing safe process systems within its scope. The shortcomings of 14C are illustrated and a method of expanding 14C to develop a comprehensive generic HAZOP review for offshore platforms is proposed. It is argued that this generic HAZOP (expanded 14C) will provide consistently higher levels of safety than applying individual HAZOP reviews to offshore platforms.

Introduction

Hazard and Operability (HAZOP) studies have been used for many years to identify potential problems with a process design. The procedure employs a multi-discipline team which discusses the design in a series of meetings. The discussion follows a standardized format: each pressure vessel or line is discussed in turn analyzing causes, consequences, and safeguards for deviations from design of selected parameters (e.g. pressure, flow, level, temperature, contamination). All deviations are considered by using a series of "key words" such as those shown in Table 1. The process proceeds from line to line and piece of equipment to piece of equipment using the procedure diagramed in Figure 1. Reference (1) discusses the problems associated with HAZOP reviews. The process is time consuming, and that the HAZOP procedure does not provide so1ut ions to problems. Different teams of evaluators may reach different conclusions as to whether causes are "realistic" and consequences "significant" requiring corrective action.

It is possible to arrive at solutions using quantified risk assessment techniques. These techniques add an additional burden of time and cost and depend on the availability of accurate reliability data. They can also give misleading results if all the assumptions built into the probability model are not accurate. For example, a recent dynamic risk assessment of single versus dual completions,(2) indicated that the more often downhole SCSSV's were tested the lower the risk of blowout. The model, however, did not include a probability that due to wear, human failure to put the valve in service after a test, etc., there is a finite probability that the very act of testing a valve would leave it in a position where it could not protect the well. If this had been considered an optimum frequency of testing would have occurred. This frequency would be dependent on the unknown assumption of rate of failure of an otherwise working device immediately following a test.

The purpose of this paper is to review whether the additional effort required to do a HAZOP on a typical offshore facility is justified, or if essentially the same results can be obtained using a generic approach similar to that used in API Recommended Practice 14C "Analysis Design Installation and Testing of Basic Surface Safety Systems for Offshore Production Platforms" (API RP 14C).