Jeeping (holiday -coating void- detection) voltages used to detect holidays in pipe coating prior to lowering in newly constructed pipe or replacement sections are dependent on the coating thickness. For example, if the pipe coating is 16 mil FBE and the girth welds are coated with DENSO Portal to 30 mils, the jeeping voltage is higher for the girth welds coatings to detect holidays. Some crews run two jeeps (holiday detectors) set at different voltages to accurately determine holidays. However, I have been on construction sites where one jeep set to the voltage for the 16 mil FBE is used also on the girth weld coating. Since they had only one jeep, it cannot be set higher as that may cause burn through from the jeep. In those cases, they were missing holidays on the girth weld coatings as the voltage was too low for proper detection.
Jeeping voltages vary from coating to coating and are not always specified on product data sheets. It may be necessary to contact the manufacturer to obtain the proper value. Also, manufacturer’s do update jeeping voltages for their coating products so periodic checks are necessary.
NACE standard SP0188 (attached) specifies tables for jeeping voltages based on coating thickness. This standard is not incorporated by reference into code (IBR’d).
Construction jeeping requirements are noted in 192.461(c) below. This comes from Subpart I which covers corrosion and includes construction and O&M maintenance of coatings. Note from the FAQ further below that failure to follow manufacturer’s recommendations is a leading cause of coating failure. Although Subpart I does not specify that operators must follow manufacturer’s recommendations for jeeping, the attached corrosion enforcement guidance for 192.461(c) does – see far below.
- 192.461 External corrosion control: Protective coating.
(c) Each external protective coating must be inspected just prior to lowering the pipe into the ditch and backfilling, and any damage detrimental to effective corrosion control must be repaired.
From the attached Pipeline Construction FAQs:
- What kinds of problems have led to coating issues?
The single most-significant cause of identified coating problems has been failure to follow manufacturer’s instructions and operator procedures. This problem has been identified in instances in which field-applied coatings have been identified as inadequate. It has also been identified in inadequate inspections of coatings using electronic defect detectors (commonly known as “jeeping”). Failure to properly prepare the pipe surface, removing all dirt and rust, has also resulted in problems.
From the attached Corrosion Enforcement Guidance Page on Jeeping (192.461(c):
Electrical testing is commonly known as “jeeping.” The voltage utilized for the electrical testing must be in accordance with the manufacturer’s recommendations or applicable industry standards. The voltage may vary with coating thickness and type; such as over girth welds, fittings, or coating repairs.
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