Bulk Tanks & Pressure Vessels

Repairs and alterations are done by organizations holding a National Board "R" Certificate of Authorization. To hold one, a shop keeps a quality manual that meets the National Board Inspection Code (NBIC), has an agreement with an Authorized Inspection Agency, passes an on-site review, and renews every three years.

Sources: National Board NB-415 · National Board R certificate

An R-1 is the Report of Repair: who did it, the owner, the item, the work, the pressure test and replacement parts. An R-2 is the Report of Alteration, which also documents design and construction separately and records the MAWP. Both are certified by the repair shop and signed off by a commissioned inspector — that paper trail keeps the vessel's code history intact.

Sources: R-1 form · R-2 form

It's the builder's certified record that the vessel meets its ASME code. If the vessel was registered with the National Board, the Board keeps it permanently, and copies can be ordered with the manufacturer's name and the National Board number. It matters when a repair or alteration is needed.

Sources: NB-264 · Order data reports · NB bulletin

It can't simply be swapped. Replacing or re-stamping a nameplate needs approval (usually from the jurisdiction where it's installed) and traceability records — what's left of the plate, purchase orders, drawings, inspection reports and the data report if available. A National Board commissioned inspector witnesses it, and any welding needs an R-stamp holder.

Source: National Board NB-136

Frost, ice patches or sweating on the outer jacket away from the piping, pressure rising unusually fast, relief valves that keep venting, and gas coming from the vacuum-space protection device. Chart's manuals say to check the vacuum with a gauge or run a normal evaporation rate test, and contact the factory if readings are poor.

Sources: EIGA Doc 224 · Chart VS/HS manual · Chart BulkLite manual

Follow the tank maker's schedule. For example, Chart's VS/HS manual says to verify relief valve settings every 2 years and replace the tank burst disc at least every 2 years — and to replace, not repair, a leaking relief valve. Industry guidance also calls for checking that relief vents aren't blocked by ice.

Sources: Chart VS/HS manual · EIGA Doc 224

It depends on the manufacturer and how the tank was built — contact the manufacturer before changing service. Some can move between atmospheric gases, but it's not a simple refill: the product-specific keyed fill fitting is changed and the tank is purged with the new product. Oxygen service needs extra care — components must be clean and oxygen-compatible. On LNG specifically: that call is ours, not a manufacturer or code requirement — we treat tanks built for LNG as staying in LNG service.

Sources: Chart VS/HS manual · Chart BulkLite manual · CGA G-4.1

This covers stationary bulk cryogenic storage of any size. A full rehab typically runs: vacuum-integrity checks on both the inner and outer vessel (warm and liquid-nitrogen-cooled), helium mass-spectrometer leak testing, perlite insulation top-off where needed, full replacement of piping, valves, regulators and safety/relief devices, exterior blasting and recoating, and a final pressure test before it's returned to service. Any welding or alteration on the pressure vessel itself falls under the R-stamp rules above, documented on an R-1 or R-2 form.

Sources: EIGA Doc 224 · National Board NB-415

The outer jacket (damage and corrosion), vacuum integrity, supports, exposed piping, paint and relief devices. Industry guidance notes the inner vessel normally doesn't need internal inspection because stored cryogens don't corrode it. Any welding on the pressure vessel falls under the R-stamp rules above.

Sources: EIGA Doc 224 · NB-415