Whatever the project may be at a site, reliability and, by extension, the meeting of uptime goals don’t just happen. As the title of this article implies, in the plant-equipment area, owner-contractor interfacing activities typically will occur during several functional project steps. These include:
♦ flow-sheet and design-specification review
♦ vendor selection
♦ pre-order review with vendors
♦ vendor drawing review
♦ inspection and test at vendor’s site
♦ review of spare parts and documentation
♦ equipment field handling and storage
♦ field installation and equipment turnover
Although the sequencing of those nine listed steps will vary for different projects, two interface functions common to all of them are of particular interest in our context. They are review and inspection. Both have a high potential for assuring that project service-factor goals, also called “availabilities,” are met.
Review functions are sometimes equated with audit activities. Reliability audits are defined as any rigorous analysis of a contractor’s or vendor’s overall design after issuing of a purchase order issue and before equipment fabrication begins. Reliability reviews are defined as a less formal, ongoing assessments of component or sub-system selection, design, execution, or testing. Sometimes, these activities involve “hold points.”
Audits and reviews are both aimed at verifying compliance with all applicable specifications. Reviews, however, also judge the acceptability of certain deviations from applicable specifications. Moreover, an experienced reliability-review specialist provides guidance on a host of items that either could not be, or simply had not been specified in writing. He /she will draw on field expertise and start-up experience when making recommendations that influence a successful plant commissioning and safe, reliable operation of the equipment for years to come. Such specialists must, by definition, work in the interfaces between owner and contractor.
A FEW NOTES ON FLOW SHEETS & SPECIFICATIONS
Flow sheets and specifications are the technical bases for interfaces with contractors’ representatives. Technical specifications are, quite simply, documents that, together with drawings and flow sheets, define in writing, 1) the plant and equipment that a purchaser wants a vendor to supply or, conversely, 2) the scope and detail that a bidder is prepared to offer the buyer.
Technical specifications define the various technical aspects of a contract. They do not concern themselves with the commercial contract conditions that are usually the subject of a separate cover letter or other binding stipulation between the two parties. Writing specifications is a skill whereby technical communications are issued in print. The owner’s representatives must write a clear, precise statement of what they want. The contractor or supplier must read, understand, and make an offer in line with the owner’s requirements.
The use of a specification requires careful consideration of needs. For example, specifying only the maximum flow rate of a cooling-water pump may be inadequate if the pump is expected to operate over a range of flow rates. Obviously, cooling-water- system resistance changes, and where a pump may work adequately in laminar flow, it may vibrate in turbulent flow and vice versa.
One thing is certain: Building reliability into a plant “up-front” is much less expensive than doing root-cause analyses (RCAs) and arguing over remedial action later.TRR
ABOUT THE AUTHOR
Heinz Bloch’s long professional career included assignments as Exxon Chemical’s Regional Machinery Specialist for the United States. A recognized subject-matter-expert on plant equipment and failure avoidance, he is the author of numerous books and articles, and continues to present at technical conferences around the world. Bloch holds B.S. and M.S. degrees in Mechanical Engineering and is an ASME Life Fellow. These days, he’s based near Houston, TX.
Tags: reliability, availability, maintenance, RAM, asset management, professional development