Q & A > Question Details
Our refinery is an old one. It already spent almost 41 yrs in operation. In this time frame we have changed our distillation column after 30 yrs and revamped topping furnace after 40 yrs. We have changed our exchangers, pressure vessels, tanks and other equipments as per inspection record and suggestion. Is there any rule of thumb regarding how often different types of refinery equipment should be renewed, e.g. after a definite period or number of operating hours?
14/09/2009 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
Equipment life will depend on the service that the equipment is in as well as operating conditions, how it was designed and how it was maintained. Besides corrosion mentioned in other replies, other degradation mechanisms can come into play such as embrittlement, creep on furnace tubes, hydrogen blistering, stress corrosion cracking, and fatigue. The right material that is operated and maintained properly can last a long time. I am aware of some vessels that were only recently replaced that were almost 100 years old. I am also aware of some valves and pumps still in operation that predate World War II.
10/09/2009 A: Mike Watson, Tube Tech International Ltd, mike.watson@tubetech.com
Plant renewal/plant life is invariably indicated by corrosion and/or erosion levels i.e. metal wall loss using periodic inspection preceded by a "quality" cleaning method. Never rely on visual or feeler gauge style inspection..ever! Better still, consider using a company such as Tubetech to modify your heat transfer plant prior to installation or at shutdown to accommodate in-situ and even on-line cleaning technology. Our simple plant design modification accommodates bespoke tube tech cleaning and inspection technology which reduces downtime and substantially enhances production. Much more cost effective than traditional water jetting. This minimises underscale corrosion which is a constant threat to plant lifecycle.
10/09/2009 A: Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
Pressure vessels are generally designed for a 25 yr life. However inspection groups will measure wall thickness every 1, 2 or 4 years depending on the service and the risk. When the corrosion allowance is depleted to the point that no more corrosion allowance exists, then the vessel must be replaced. So the vessel life will depend on the corrosion rates that the vessel, or piping is subjected to over its service life.