Recently I had a client who made alterations to a pressure vessel (PV) in an ammonia refrigeration process that required the PV to be re-certified. The state where this PV resides is a “coded state”, meaning they have adopted ASME Code for the PVs within the state. So, the contractor making the alterations had scheduled the Authority Having Jurisdiction (AHJ) (in this case it was an insurance agent) to be present for the state inspection following the alteration(s). And this is where the state PV code and PSM/RMP practices part ways…
The contractor making the PV alteration has a company policy to pressure test the PV to 50 psi after the alterations are complete and is done by inserting a rubber plug into the open nozzle. The insurance inspector witnessed the contractor to pressurize the vessel to 50 psi as a means to “test” the integrity of the alterations. For the life of me, and those more “in the know” than I, we have no idea where the 50 psi came from. I can only assume this is done when piping to and from a PV is not complete and where the inspector has a propensity for visual inspections. The state code for PV’s does allow the inspector a lot of latitude in how he/she validates the alteration/repair of the PV, but it is amazing that the AHJ allowed only 50 psi, knowing the normal pressure in this vessel could be in the 105-190 psi range on the summer months; so, 50 psi does not even come close to be “normal operating pressure”, much less the MAWP!
So here is the language from the state PV code and the NBIC (as referenced by the state code)
Rule 3.4.10. Major Repairs
Where repairs are necessary, which in any way affect the working pressure or safety of a boiler or pressure vessel, an inspector shall be called for consultation and advice as to the best method of making such repairs. After such repairs are made, they shall be reviewed by and found acceptable to an inspector. Repairs to all boilers and pressure vessels shall conform to the applicable provisions of the National Board Inspection Code.
Here is the NBIC requirements for NDE/NDT for alterations… (emphasis by me)
4.4.2 TEST OR EXAMINATION METHODS APPLICABLE TO ALTERATIONS
The following requirements shall APPLY TO ALL REPAIRS AND ALTERATIONS to pressure-retaining items:
a) The integrity of repairs, alterations, and replacement parts used in repairs and alterations shall be verified by examination or test;
b) Testing methods used shall be suitable for providing meaningful results to verify the integrity of the repair or alteration. Any insulation, coatings, or coverings that may inhibit or compromise a meaningful test method shall be removed, to the extent identified by the Inspector;
c) The “R” Certificate Holder is responsible for ALL ACTIVITIES RELATING TO EXAMINATION AND TEST of repairs and alterations;
d) Examinations and tests to be used shall be subject to acceptance of the Inspector and, where required, acceptance of the Jurisdiction.
4.4.1 TEST OR EXAMINATION METHODS APPLICABLE TO REPAIRS
Based on the nature and scope of the repair activity, one or a combination of the following examination and test methods shall be applied to repairs and replacement parts used in repairs.
a) Liquid Pressure Test
Pressure testing of repairs shall meet the following requirements:
1) Pressure tests shall be conducted using water or other liquid medium. The test pressure shall be the minimum required to verify the leak tightness integrity of the repair. The test pressure shall not exceed the maximum liquid test pressure of the original code of construction. When original test pressure included consideration of corrosion allowance, the test pressure may be further adjusted based on the remaining corrosion allowance.
2) During a pressure test where the test pressure will exceed 90% of the set pressure of the pressure relief device, the device shall be removed whenever possible. If not possible, a spindle restraint may be used following the valve manufacturer’s instructions and recommendations. Extreme caution should be employed to ensure only enough force is applied to contain pressure. Excessive mechanical force applied to the spindle restraint may result in damage to the seat and/or spindle and may interfere with the proper operation of the valve. The spindle restraint shall be removed following the test. The organization that performs the pressure test and applies a spindle restraint shall attach a metal tag that identifies the organization and date the work was performed to the pressure relieving device. If the seal was broken, the organization shall reseal the adjustment housing with a seal that identifies the responsible organization. The process shall be acceptable to the Jurisdiction where the pressure-retaining items are installed.
3) The metal temperature for the pressure test shall be in accordance with the original code of construction, but not less than 60°F (16°C) unless the owner provides information on the toughness characteristics of the material to indicate the acceptability of a lower test temperature. For thick walled pressure retaining items, it is recommended to seek technical guidance in establishing the notch toughness characteristics of the steel prior to pressure testing so that the metal temperature may be warmed above 60° F (16°C) to avoid brittle fracture. During close examination the metal temperature shall not exceed 120°F (49°C), unless the owner specified requirements for a higher test temperature, and it is acceptable to the Inspector.
4) Table 4.4.1 (see code)
5) Hold-time for the pressure test shall be a minimum of 10 minutes prior to examination by the Inspector. Where the test pressure exceeds the MAWP of the item, the test pressure shall be reduced to the MAWP for close examination by the Inspector. Hold-time for close examination shall be as necessary for the Inspector to conduct the examination.
b) Pneumatic Test
A pneumatic test may be conducted. Concurrence of the owner shall be obtained in addition to that of the Inspector and Jurisdiction where required. The test pressure shall be the minimum required to verify leak tightness integrity of the repair, but shall not exceed the maximum pneumatic test pressure of the original code of construction. Precautionary requirements of the original code of construction shall be followed;
c) Initial Service Leak Test
When an initial service leak test is permitted by the original code of construction, such testing may also be used to verify the leak tightness integrity of repairs;
d) Vacuum Test
A vacuum test may be conducted. Vacuum test methods used shall be suitable to verify the leak tightness integrity of the repair;
e) Nondestructive Examination (NDE)
NDE may be conducted. NDE methods used shall be suitable for providing meaningful results to verify the integrity of the repair. Exclusive use of visual examination (VT) is only permitted with the following considerations:
1) When a pressure test or alternative NDE methods other than visual examination, are not practicable the exclusive use of direct VT as an NDE method shall be limited to routine repairs, as identified in NBIC Part 3, 3.3.2.
2) For each repair being considered, the exclusive use of direct VT as an NDE method shall be acceptable to the Inspector, and where required, the Jurisdiction.
3) As a minimum, direct VT shall be performed after the root weld layer or first-pass is deposited, and the final weld surface. Other weld layers shall be examined as identified by the Inspector and, where required, the Jurisdiction.
4) Personnel completing direct VT shall be qualified and certified in accordance with paragraph NBIC Part 3, 4.2- b), AWS QC-1, or any nationally recognized standard acceptable to the Jurisdiction. Visual acuity shall be demonstrated using as a minimum, standard J-2 letters on standard Jaeger test type charts for near vision.
5) Direct VT shall be performed in accordance with a written procedure meeting the procedure and reporting requirements listed in the original code of construction or ASME Section V, Article 9.
So, as we can see, per the state code and NBIC, the vessel should have been subjected to a pressure test not less than that required by the code of construction (e.g. the nameplate MAWP). This particular vessel has an MAWP of 250 psi; not the 50 psi requested by the AHJ.
Now here is the “kick in the ass” part of this incident… the process safety professional overseeing the repair, went above and beyond the State’s required pressure test and required the contractor to pressure test at a higher pressure as a means to verify both the integrity of the PV and its associated piping. And although the vessel passed the 50-psi test witnessed by the inspector, it failed the higher test pressure.
Had the facility introduced liquid ammonia to the vessel WITHOUT having done a more thorough pressure test, they would have discovered the leak with a vessel full of ammonia!!!! And guess who would have been up the creek without a paddle… the host facility – under the PSSR requirements. The state AHJ would be 0% responsible and in all likelihood, the contractor would not be cited either. The facility is the “owner/operator” of the vessel and thus the responsibility for it lies with them.
So why would OSHA/EPA take issue with a facility who makes the alterations/repair per the PV code and then follows something less for the NDE/NDT of the alteration/repair as requested by the state inspector?
Well, first off, this PV code applies to all PV’s. So, the same code would apply to an “air receiver” vs. our ammonia “High-Pressure Receiver”. Looking at the consequences of both failing in the same mode, I think we can all agree that the Ammonia HPR (High-Pressure Receiver) would have far more significant consequences that would extend out further than the “air receiver”. And this, folks, is why in PSM/RMP management we must adopt our RAGAGEP for altering/repairing our covered equipment AND not merely rely on the state PV code! The state PV code is intended to establish a “floor” for the absolute minimum requirements for managing ALL pressure vessels, regardless of their contents. Remember… one of the first incidents that brought out the boiler and pressure vessel code was the failure of a molasses tank in Boston!
Our PSM/RMP management system needs to adopt an actual RAGAGEP for these repairs and REGARDLESS of what some state AHJ requires OR, we MUST meet our chosen RAGAGEP (as this facility did). And, this also leads us right back to the contractor qualification process by which PSM/RMP requires and the applicable RAGAGEP used by those contractors. Now if the business wants to manage their non-PSM/RMP PVs at the state minimum’s that’s a risk they choose to make; however, let’s not lose site of how EPA’s Worst-Case Off-Site Consequence Analysis (OCA) is defined! If we do not want that Worst-Case Scenario to become a reality, then it is up to us to manage our covered PV’s to a higher level.