Following the nurse tank safety advisory issued earlier this year by the Federal Motor Carrier Safety Administration (FMCSA) and the Pipeline and Hazardous Materials Safety Administration (PHMSA), you may find yourself needing to perform additional testing and repairs on a nurse tank. Here are three things to know:
1. Your ASME Plate Is Important
The American Society of Mechanical Engineers (ASME) plate determines how a tank should be inspected and tested. If the plate is currently in good shape and valid, there is no required periodic testing or inspection. Nurse tanks with missing or illegible ASME plates need to conduct voluntary visual inspections, thickness testing and pressure testing at least every five years.
The exception, however, is if your tank is effected by the advisory that was issued. This would be tanks that were manufactured between Jan. 1, 2007 to Dec. 31, 2011 by American Welding and Tank (AMT) at its Fremont, Ohio plant. FMCSA and PHMSA strongly encourage owners of these tanks to conduct this routine testing, regardless of ASME plate status.
As far as whether or not testing should be required for all nurse tanks, Jessica Stiles of FMCSA says a change isn’t off the table.
“Any such rulemaking would take years, and we would have to get input from all of you as well,” Stiles explains on a recent Ag Retailers Association webinar. “We would have to issue a request for information, figure out what all of you would like to see, and also what kind of cost that would be to the businesses. It is on the radar. We have talked for years about how we can make improvements to nurse tanks.”
2. Recognizing Failures During Inspection
If something is failing on one of your tanks, Alex Cheng of PHMSA says it will often be obvious during a visual inspection.
“Usually there’s kind of a bulging on the nurse tank. If you notice any dents, gouges, corrosion, that’s very easy to pick up,” Cheng says. “These are really tell-tale signs to stop work, take action and see if there are any other issues with the tank.”
A failure during thickness testing depends on the volume of the tank.
- Volume of <1,500 gallons: minimum head thickness is 0.203” and minimum shell thickness is 0.239”
- Volume of >1,500 gallons: minimum thickness is 0.250”
“If the thickness measurements that come out from your test are less than what is cited on the ASME data plate, it doesn’t necessarily mean the tank is going to fail, and the reason why is because ASME is only using nominal thickness, whereas the thickness test is measuring the minimum thicknesses,” Cheng explains. “More information may be needed, and you may have to reach out to the manufacturer. The manufacturer can provide a report that says what the minimum thickness calculations are.”
3. Repair Rules
In order to repair a nurse tank, the repair alteration must be authorized by your local jurisdiction and your ASME plate must be attached and legible.
“There are plates that are attached, but you can’t read them. Nurse tanks with illegible ASME plates cannot be repaired,” warns PHSMA’s Leonard Majors. “Unauthorized repairs on a nurse tank will place it out of service.”
Majors adds repairs must be done in accordance with the original code of construction of the tank, follow procedures outlined in the National Board Inspection Code (NBIC), and the repair facility must have an “R” stamp.
“The “R” stamp means that they are registered and authorized through NBIC to perform repairs on pressure vessels,” Majors says. “The R stamp facility may review the ASME plate or additional information, such as thicknesses, material and construction, and use this information, as well as their expertise, to determine what type of repair should be performed.”
Following the repair, the facility will apply an additional plate to the tank, which will be marked with the “R” stamp. The original ASME plate will remain on the tank as well.
