Improving Machinery Reliability

Heinz P. Bloch

• Publisher: Gulf Professional Publishing
• Year: 1998
• ISBN:
  9780080508542
• Edition: 3
• Topic: Technology & Engineering
• Subtopic: Mechanical Engineering
• Index: Technology & Engineering

This totally revised, updated and expanded edition provides proven techniques and procedures that extend machinery life, reduce maintenance costs, and achieve optimum machinery reliability. This essential text clearly describes the reliability improvement and failure avoidance steps practiced by best-of-class process plants in the U.S. and Europe.

Chapter 1

Requirements Specification

Long before machinery specifications can be prepared, the plant designers perform scoping studies encompassing a large number of options. Process and economic considerations are weighed, compared, and analyzed. Design philosophies are debated at the highest levels of management, business forecasts are studied, and thousands of questions are asked and answered before the machinery engineer is given his first opportunity to prepare an inquiry document for major machinery or detailed purchase specification packages for all the machinery in a process plant.

To the superficial observer, the job of specifying machinery would seem rather routine. But an experienced engineer knows that this is far from true. Ticking off a few check marks on a form sheet may define the extent of supply, but it certainly cannot pass as an adequate specification for major machinery. Then again, excessively bulky specifications may have the effect of frightening the bidder into adding significant extra charges for potential oversights, and badly worded specifications may prompt cost escalation to cover potential misunderstandings. At times a combination of bulk, cross referencing of many specification documents, and wording subject to misinterpretation has motivated vendors to decline to bid. As if this were not bad enough, an ill-conceived specification may burden process plants with the perennial “bad actor”—a piece of maintenance-intensive machinery not bad enough to replace with something new or different, but bad enough to drive up maintenance costs, sap maintenance manpower, and cause feelings of resignation or demotivation in personnel.

A good specification, therefore, is concise and precise. It will have to define your requirements in clear, understandable form. Yet it should encourage the vendor to offer more than the bare minimum requirements. Your next process plant should benefit from advances in the state-of-the-art of which the vendor may have knowledge if your joint, conscientious screening efforts can certify these changes to be safe, economic, and not prove to introduce downtime risks.

Industry Standards Available for Major Machinery in Process Plants

Table 1-1 represents a listing of presently available API (American Petroleum Institute) standards. These specifications were developed by panels of user engineers to define petrochemical process plant machinery in a professional fashion. Wherever possible, API standards should become the focal point document in machinery specifications for process plants.

Table 1-1

Principal API Standards for Mechanical Equipment (1997)

Standard	7B-11C	Specifications for Internal-Combustion Reciprocating Engines for Oil Field Service
Standard	541	Squirrel Cage Induction Motors—250 HP and Larger
Standard	546	Brushless Synchronous Machines—500kVA and Larger
Standard	610	Centrifugal Pumps for General Refinery Services
Standard	611	General-Purpose Steam Turbines for Refinery Services
Standard	612	Special-Purpose Steam Turbines for Refinery Services
Standard	613	Special-Purpose Gear Units for Refinery Services
Standard	614	Lubrication, Shaft-Sealing, and Control Oil Systems for Special-Purpose Applications
Standard	616	Gas Turbines for Refinery Services
Standard	617	Centrifugal Compressors for Petroleum, Chemical, and Gas Service Industries
Standard	618	Reciprocating Compressors for Petroleum, Chemical, and Gas Service Industries
Standard	619	Rotary-Type Positive Displacement Compressors for General Refinery Services
Standard	670	Vibration, Axial Position and Bearing-Temperature Monitoring Systems
Standard	671	Special-Purpose Couplings for Refinery Services
Standard	672	Packaged, Integrally Geared, Centrifugal Plant and Industrial Air Compressors for Petroleum, Chemical, and Gas Service Industries
Standard	674	Positive Displacement Pumps—Reciprocating
Standard	675	Positive Displacement Pumps—Controlled Volume
Standard	676	Positive Displacement Pumps—Rotary
Standard	677	General Purpose Gear Units for Refinery Services
Standard	678	Accelerometer-Based Vibration Monitoring System
Standard	681	Liquid Ring Vacuum Pumps and Compressors for Petroleum, Chemical, and Gas Industries Services
Standard	682	Shaft Sealing Systems for Centrifugal and Rotary Pumps
Standard	683	Rotor Dynamics and Balancing
Standard	686	Machinery Installation and Installation Design

Nevertheless, major U.S. petrochemical plants or contractors will rarely opt to use applicable API standards as the only procurement standard for machinery. Either the contractor or the plant owner, or both, makes use of specification supplements or design and construction standards reflecting particular experience, special needs, regional requirements, design and maintenance philosophies, and the like. All of these supplements serve a specific purpose. Compliance with government regulations, uniformity of training for operators or mechanics, common spare parts utilization among affiliated plants, utilization of locally available components, and a host of other purposes could be mentioned. The relative importance of these factors will change from plant to plant and from location to location. Unfortunately, so does the specification format—to the detriment of all parties involved.

How to Deal with the Typical API Data Sheet

API Standard 617, “Centrifugal Compressors for General Refinery Services,”^* is the primary reference document for procuring a given centrifugal compressor. It contains nine data sheets that are to be filled in by the purchaser—usually a major contracting or design firm acting on the owner’s behalf—to the extent necessary to define the plant or process requirements. All remaining data must be provided by the vendor. Five of these data sheets merit closer examination.

Our review of the API centrifugal compressor data sheets will be representative of the structured approach recommended for all API-based machinery. It will be restricted to those items having an impact on successful startup, operation, reliability, and maintainability of centrifugal compressors.

On page 1 of the data sheets (Figure 1-1), we have drawn attention to the check point “as built.” (The relevance of “as built” data is further highlighted in Figures 1-27 and 1-30.) Dimensional records are so important to turnaround maintenance, emergency repairs, and general troubleshooting that submission of these data should be made a c...

Table of contents

• Cover image
• Title page
• Table of Contents
• Inside Front Matter
• Copyright page
• Preface
• Introduction
• Chapter 1: Requirements Specification
• Chapter 2: Vendor Selection and Bid Conditioning
• Chapter 3: Machinery Reliability Audits and Reviews
• Chapter 4: Maintenance and Benchmarking Reliability
• Chapter 5: Life Cycle Cost Studies
• Chapter 6: Extending Motor Life in the Process Plant Environment*
• Chapter 7: Equipment Reliability Improvement Through Reduced Pipe Stress*
• Chapter 8: Startup Responsibilities
• Chapter 9: Spare Parts and Their Effect on Service Factors
• Chapter 10: Maintenance for Continued Reliability
• Chapter 11: Maintenance Cost Reduction
• Chapter 12: Lubrication and Reliability
• Chapter 13: Providing Safety and Reliability Through Modern Sealing Technology
• Appendix A: Useful and Interesting Statistics
• Appendix B: Common Sense Reliability Models
• Index