Operating Procedures in the Process Industries

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The contents of this page are based on the ebook Operating Procedures and on Chapter 9 of the book Process Risk and Reliability Management. Sample pages from the ebook can be downloaded here.

The definition of operating procedures used here is:

Operating procedures are written instructions that, when carried out by the operations personnel, will minimize deviations from design or operating intent.

The key terms used in this definition are discussed below.

Operations

Operating procedures should be written for operators, supervisors, and line managers. Other users, such as engineers, auditors and technical experts may use the procedures, but generally their requirements are secondary; the operators are the primary customers of the procedures.

In practice operating procedures are usually expected to serve different goals. There is nothing inherently wrong with this requirement, as long as the nature of the separate goals is understood and the manual is organized so that they are handled appropriately. The following is a list of some of the varied goals that a manual is often expected to address.

1. Provide brief, checklist-type instructions to operators who are fully trained and who are very familiar with the facility and its operation.
2. Provide detailed instructions for operators who are experienced in general facility operations, but who do not know the particular unit for which the procedures were written.
3. Provide background and reference information, such as Material Safety Data Sheets (MSDS) and safe operating limit values.
4. Describe what to do in the event of a major emergency.
5. Describe what to do in the event of an environmental upset, including the procedure for contacting the appropriate regulatory agencies.

As well as understanding the profile of the person(s) who will be using the procedures, it is also important to understand the physical and social context in which the manual will be used. For example, operators and maintenance technicians often work outside, where they have to contend with high or low temperatures, wind, rain and snow. If they work indoors noise and confined space access could be an issue. The operating and maintenance manuals should be written and published in a manner such that it is useful to the operator in the place where he or she is actually working.

In many cases the operator using a manual will not be sitting at a desk with the book directly in front of him; instead he or she will often be at a control panel trying to following instructions from a manual that is placed on a table at some distance, or he may be attempting to read the manual while repairing a piece of machinery. In cases such as these, it makes sense to print the instructions in large type so that they can be read at a distance.

A manual is judged not by its appearance, the quality of its written English, the exactitude of the contents, or the sophistication of the software used to deliver those contents - such attributes are merely factors affecting the ultimate usefulness of a manual; instead, an operating manual is judged by its usefulness to the persons using it. Hence, a shabby, old-fashioned, battered, coffee-stained manual that is frequently used is better than a slick, colorful, user-friendly document that it stays on the shelf. If the operators choose not to use a manual, then they will not use it; it cannot be forced upon them. Therefore it is the responsibility of those who are writing and publishing the manual to develop a product that is genuinely useful.

Written Instructions

Operating procedures must be written down (either on paper or in an electronic file). Sometimes the operators may have a good set of informal, oral procedures that has never been committed to paper. In these situations, the procedures-writing project consists largely of writing down that informal information in a clear and organized manner.

Design or Operating Intent

Before procedures can be written, management and the operators must clearly define how the facility is to be run; in other words they must determine the design or operating intent for their unit. In particular, target conditions for all flows, pressures and temperatures have to be specified, along with the allowable deviations from those target conditions.

Design and operating intent must be quantified. For example, the following instruction (which is somewhat tongue in cheek) is totally qualitative, and so is not of much value to the operator who is expected to follow it.

• Increase the bottoms temperature gradually until the overhead pressure is about normal.
  

The above instruction can be re-written more precisely as:

• Increase the bottoms temperature by 5C every 10 minutes as measured by TI-213.

• When the overhead pressure reaches 3.4 barg as measured by PIC-221, stop the temperature increase.

The permissible overhead pressure range is 3.0 - 4.0 barg. If the pressure deviates outside this range, refer to Instruction XYZ.

The adverb "gradually" in the first text box has been replaced with numerical rate values. The word "normal" has been replaced with a number and a safe range.

In the same vein, terms such as "crack the valve open" are unhelpful because they are non-quantitative. Even a phrase such as "open the valve two turns" could lead to an error were the valve trim to be changed. It would be better for the procedures to read, "Open the valve so that the liquid flow, as measured by FR‑203, is in the range 90-100 gpm".