ASME Section VIII, API 650, API 620 & UL 142 Code-Stamped Steel Vessels
ASME Section VIII Division 1 pressure vessels, API 650 welded aboveground storage tanks, API 620 low-pressure gas-storage tanks, UL 142 fuel oil tanks, and National Board registered code work — from 100-gallon lab vessels to 100,000-gallon field-erected terminals.
Code-stamped steel fabrication operates under the tightest quality regime in the tank industry. ASME Boiler & Pressure Vessel Code Section VIII Division 1 governs pressure vessels — any welded vessel holding gas or liquid at 15 psig or above and 6 inches diameter or larger. The code prescribes minimum wall thickness, weld-joint categories, radiographic inspection requirements, material test reports, and stamping protocols. Vessels fabricated to Section VIII are U-stamped by an ASME-certified shop, National Board registered, and accompanied by a Manufacturer's Data Report (Form U-1).
API 650 governs welded aboveground storage tanks for petroleum, chemical, and water service from 20 feet through 300+ feet in diameter. It defines shell-thickness calculations, roof designs (fixed-cone, floating, geodesic dome), wind-load and seismic-load requirements, foundation considerations, and inspection protocols. API 620 extends the same framework to low-pressure gas-storage tanks operating up to 15 psig. API 653 governs in-service inspection and repair. UL 142 covers aboveground flammable-liquid tanks — fuel oil, gasoline, diesel, and similar — with specific emphasis on fire-resistant construction, double-wall configurations, and secondary containment.
Code work is documentation work. Every heat of steel carries a Material Test Report (MTR) traced through fabrication. Every weld is logged with welder ID, procedure (WPS), and inspection record. Critical welds receive radiographic inspection (RT) or ultrasonic inspection (UT), witnessed by an authorized inspector from the Authorized Inspection Agency. The finished vessel carries a hydrostatic test (hydro) at 1.3x design pressure, documented on a Form U-1 signed by the Authorized Inspector. The documentation package — MTRs, weld maps, NDE reports, hydro test record, U-1 — travels with the vessel through its service life and is referenced for every future inspection, repair, or re-rate.
What We Fabricate
ASME Section VIII Pressure Vessels
Code-stamped, National Board registered, U-1 documented pressure vessels from 100-gal lab through 50,000-gal field.
API 650 Welded Storage Tanks
Aboveground welded storage tanks from 20-ft through 300+-ft diameter, fixed-cone or floating-roof.
API 620 Low-Pressure Tanks
Welded low-pressure gas-storage tanks to 15 psig design pressure.
UL 142 Aboveground Fuel Tanks
Fire-resistant fuel-oil, diesel, gasoline, and flammable-liquid storage — double-wall or F911 options.
Double-Wall Containment Tanks
Integral secondary-containment vessels for EPA SPCC and fire-code compliance.
Horizontal Pressure Vessels
Saddle-supported cylindrical vessels for gas receivers, separators, and accumulators.
Vertical Pressure Vessels
Leg-, skirt-, or lug-supported vertical vessels for reactor and process service.
Reactor Vessels
Jacketed, agitated, baffled code-stamped reactors for chemical and pharmaceutical batch processing.
Heat Exchanger Shells
Shell-and-tube, U-tube, and fixed-tubesheet exchanger shells fabricated to TEMA and ASME.
Oil-Water Separators
API 421 horizontal and vertical separators for petroleum and chemical plant use.
Field-Erected Storage Tanks
On-site fabrication and erection of large-diameter API 650 tanks.
Code Repair & Re-Rate
API 653 in-service repair and re-rating of existing code-stamped tanks.
How a Custom Project Works
Requirements capture. Volume, materials of construction, service chemistry, operating temperature and pressure, installation footprint, utility connections, code and finish requirements. We work from a specification sheet you provide or we draft one against your process flow.
Engineering and drawings. Our partner engineering team produces a general-arrangement drawing, bill of materials, weld-map, and code calculation package if applicable. You review and sign off before any steel is cut.
Material procurement. Plate, pipe, fittings, and elastomers are ordered against the approved BOM. Material Test Reports (MTRs) are captured for every heat of stainless or carbon steel used on code work.
Fabrication. Shell courses rolled and seam-welded, heads formed and welded, ports installed per drawing. Sanitary work is TIG-welded with argon purge and ground flush to 32 Ra or better on product-contact surfaces.
Inspection and testing. Radiographic or ultrasonic weld inspection where code requires, hydrostatic pressure test at 1.3x design pressure for code vessels, surface-roughness profilometry on sanitary vessels, passivation to ASTM A967.
Documentation and shipment. MTRs, weld maps, NDE reports, hydro certificates, code stamps, and ASME Form U-1 (if applicable) are bound into a documentation package that travels with the vessel. Shipment via flatbed or step-deck with blocking, bracing, and tarp as specified.
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Frequently Asked Questions
Does a vessel need to be U-stamped?
Only if the service requires it. OSHA, state pressure-vessel laws, insurance carriers, process licensors, and customer quality programs can each impose code requirements. Not all pressure vessels require a U-stamp — some state laws exempt vessels under 15 psig or under a certain volume. When in doubt, code-stamp.
What's the difference between API 650 and API 620?
API 650 covers welded aboveground storage at atmospheric pressure (up to 2.5 psig). API 620 extends to low-pressure designs up to 15 psig — typical for LPG, ammonia, and some chemical-vapor storage. Above 15 psig, tanks fall under ASME Section VIII as pressure vessels.
Do I need a field-erected tank?
Yes, for any tank over approximately 12-ft diameter by 40-ft height — larger than what fits on a truck. Field erection on a prepared foundation is standard for API 650 tanks above 20-ft diameter. The fabricator ships pre-cut plate, shell courses, and roof components; field crew welds on site.
How long does an ASME pressure vessel project take?
Small off-the-shelf ASME vessels (code-stamped standard-design receivers, separators) can ship in 4–8 weeks. Custom-engineered pressure vessels typically take 14–26 weeks. Large field-erected API 650 tanks run 20–40 weeks depending on size, location, and weather.
Give us your process specs — volume, service chemistry, installation footprint, utility connections, finish requirements. We come back with a full engineering package, firm lead time, and fixed price. No obligation, no sales pressure.
