Each year about this time I get at least one phone call from a member/client about their annual “holiday inspection”; trust me when I say the term “holiday” has absolutely no relation to the Thanksgiving or Christmas holidays! However, their CMMS has spit out a work order that calls for a piping circuit to be inspected and the inspection is called a “holiday inspection”. This has gotten to the point that we now will make sure that any holiday inspections are not scheduled for November/December time frame. So then what is a “holiday inspection”?
Does your piping have a coating on it?
If it does, then your piping inspection program should have a “holiday inspection” protocol.
What is a “holiday”?
A “holiday” is a hole or void in the coating which exposes the pipe (in this situation – could be a vessel as well) to corrosion. A holiday, in relation to an anticorrosion surface coating, can be defined as:
- A discontinuity in coating, when a part of the surface remains uncoated
- A defect such as an area of insufficient coating film thickness
- A pinhole within the coating
- A crack within the coating
- An improper adhesion or bonding of the coating
Why do they call that a “holiday”?
That is a very good question with a very interesting story… The term holiday is said to date back to the days of wooden ships. Sailors were required to seal the mast of the ship with tar to prevent the wood from rotting. If a sailor missed coating an area of the mast, it was said, the “sailor must have taken a holiday at that point”. And as far as I can tell that is actually where the term came from and it has carried on into today’s terminology.
So what should my piping inspection program require when my piping has a required coating to comply with my chosen RAGAGEP?
First and foremost, most underground piping will have a coating and this piping’s coating must be fully inspected for “holidays”. But we also have a lot of above grade piping that will have a required coating. PLEASE keep in mind that even if it is ONLY your company’s pipe spec that calls for a coating to aid in the slowing of external corrosion, your piping inspection program MUST include an inspection of this coating(s). The most widely used piping inspection RAGAGEP is API 570 and it states the following:
9.2.3 Pipe Coating Holiday Survey
The pipe coating holiday survey can be used to locate coating defects on buried coated pipes, and it can be used on newly constructed pipe systems to ensure that the coating is intact and holiday-free. More often it is used to evaluate coating serviceability for buried piping that has been in-service for an extended period of time.
From survey data, the coating effectiveness and rate of coating deterioration can be determined. This information is used both for predicting corrosion activity in a specific area and for forecasting replacement of the coating for corrosion control.
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9.3.3 Pipe Coating Holiday Survey
The frequency of pipe coating holiday surveys is usually based on indications that other forms of corrosion control are ineffective. For example, on a coated pipe where there is gradual loss of cathodic protection potentials or an external corrosion leak occurs at a coating defect, a pipe coating holiday survey may be used to evaluate the coating.
How are “holiday inspections” conducted?
“Holiday inspections” are performed using specialized equipment divided into two main groups:
- low and
- high voltage testers
Low voltage holiday testers are used for coatings up to 20 mils DFT. High voltage testers produce up to 40,000 volts of pulsed DC current. There are several industry standards regarding holiday testing including ASTM D-4787 & D-5162 and NACE RPO 188-88.
So although the name sounds appropriate for this time of the year, a holiday inspection is nothing to joke about and plays a critical role in pipe integrity when the pipe is “coated”. Our programs must address this type of inspection in order to fully comply with PSM/RMP Mechanical Integrity requirements.