November 2011

Special Report: Plant Safety and Environment

Relief device inlet piping: Beyond the 3 percent rule

With careful consideration, an engineer can be certain that an installation will not chatter

Smith, D., Smith & Burgess LLC; Burgess, J., Smith and Burgess LLC; Powers, C., Smith and Burgess

Good engineering practices (API STD 520 and ASME B&PV Code Section VIII) have long specified/required that inlet piping pressure drop from the vessel to the safety relief device should be limited to no greater than 3% of the safety relief valve’s set pressure. Many companies have taken a more lenient approach to the inlet pressure loss limits; consequently, many installations do not meet the 3% design guideline, as the prevailing company logic assumed that existing installations were “safe” as long as the inlet losses were less than the safety relief device’s blowdown with some built-in safety margin. Up until recent fines by OSHA, there have been no hard and clear indu

Log in to view this article.

Not Yet A Subscriber? Here are Your Options.

1) Start a FREE TRIAL SUBSCRIPTION and gain access to all articles in the current issue of Hydrocarbon Processing magazine.

2) SUBSCRIBE to Hydrocarbon Processing magazine in print or digital format and gain ACCESS to the current issue as well as to 3 articles from the HP archives per month. $409 for an annual subscription*.

3) Start a FULL ACCESS PLAN SUBSCRIPTION and regain ACCESS to this article, the current issue, all past issues in the HP Archive, the HP Process Handbooks, HP Market Data, and more. $1,995 for an annual subscription.  For information about group rates or multi-year terms, contact email Peter Ramsay or call +44 20 3409 2240*.

*Access will be granted the next business day.

Related Articles

From the Archive



{{ error }}
{{ comment.comment.Name }} • {{ comment.timeAgo }}
{{ comment.comment.Text }}