Write a field test procedure as described in Annex A of the API 688 PDF. Specify accelerometer locations, data recording duration (minimum 20 minutes), and acceptable tolerance bands for agreement between predicted and measured results (typically within 20%).
The functions as the master reference for mechanical engineers, safety managers, and plant designers to model, analyze, and mitigate these severe industrial risks. Licensed digital copies of the standard can be acquired directly through authorized distributors such as the Accuris Standards Store or Intertek Inform .
The standard was developed to clarify and expand upon the complex vibration sections (specifically Clause 7.9) of , which is the primary standard for reciprocating compressors. Scope of the Standard
Altering the lengths of pipe runs or changing the placement of elbows to shift the system's natural acoustic frequencies away from the pump’s operating frequencies.
: Determine the cylinder count, operating speed range, and gas properties. api 688 pdf
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The standard defines how acoustic pulsations are generated and how they propagate through piping systems. It details the requirements for performing (analog or digital) to predict pulsation levels. Furthermore, it outlines the design and application of pulsation suppression devices, such as:
Tuned to specific frequencies to block damaging pulsations. 2. Mechanical Analysis and Piping Design
For engineers, operators, and asset managers seeking the "API 688 PDF," understanding the core principles, methodologies, and design philosophies contained within this document is essential for ensuring system reliability. This article provides an in-depth breakdown of API 688, its structural analysis approaches, and how it safeguards industrial piping systems. 1. What is API 688? Write a field test procedure as described in
The primary goal of API 688 is to provide technical requirements and guidance to minimize fatigue, structural damage, and mechanical failure caused by pressure pulsations in piping systems. It consolidates vibration control requirements that were previously scattered across various individual equipment standards. Reciprocating compressors (formerly under API 618). Rotary-type PD compressors (e.g., screw compressors). Reciprocating PD pumps (formerly under API 674). Controlled volume PD pumps. Rotary PD pumps. Key Content and Analysis Methods
Combined acoustic and mechanical analysis. This pairs the acoustic simulation of M2 with a mechanical finite element analysis (FEA) of the piping system. It predicts actual mechanical stresses and ensures compliance with fatigue life limits.
: For high-level summaries of changes between editions (such as from the 1st to 2nd edition), you can find technical reports and reviews on platforms like Scribd or from industry groups like the European Forum for Reciprocating Compressors (EFRC) . RP 688 pages.fm
: Uses simplified formulas, empirical charts, and standard dampener sizing rules. Licensed digital copies of the standard can be
A deep dive into the reveals several critical sections detailing how to analyze, design, and modify compressor systems to ensure integrity: 1. Acoustic Simulation and Pulsation Suppression
Collaborate with the pump vendor and third-party vibration specialists early to determine whether Design Approach 1, 2, or 3 is required.
Properly sizing the pulsation bottles on suction and discharge.
The American Petroleum Institute (API) addresses these risks through specialized standards. While standards like outline the design requirements for reciprocating compressors, API 688 serves as the dedicated technical report for pulsation and vibration control.
Medium-risk systems where empirical calculations are insufficient to guarantee safety.