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Antonius renews NORSOK vessel head certification

Last november, Antonius renewed its NORSOK certification for another 5 years. Antonius is one of the few manufacturers able to produce vessel heads that meet the NORSOK standard. In this article, Marco Hamersma shares how the company is able to consistently meet this standard and how it impacts their operation. He also shares which manufacturing processes, and which materials, Antonius is certified to work with.

Process technology is, especially in the oil & gas market, often installed at interesting locations such as the ocean shore or even on offshore platforms where salt water and arctic temperatures stress even the highest quality materials. Vessel heads are part of the installations used to store, transport or process oil or gas that often has aggressive characteristics – at high pressures and/or temperatures. It is no surprise that this equipment has to meet stringent requirements in terms of quality and safety. To obtain the highest quality of the equipment, the Norsok Standard is applied for the manufacturing of the parts and material being used.


NORSOK is the name of the standard developed by the Norwegian petroleum industry to improve every aspect of the quality of their production field. It was introduced in 1994 to cut cost and improve competitiveness on the Norwegian continental shelf. The standard aims to ensure not only quality and cost effectiveness but also improve safety by ensuring, for example, that components such as vessel heads are made to the necessary specifications.

Meeting the requirements of the NORSOK standard is not something to be taken lightly. It places high demands on the organization in terms of ISO work-procedures and, of course, safety, but most of all on the quality of our machines. Take our annealing furnaces, for example. During the certification process, the furnaces temperature can only deviate 10 degrees Celsius between 40 measuring points. For the big furnace we have that goes up to 7,2 meters in diameter, it requires tireless maintenance to keep this equipment in peak state.

A practical look at NORSOK

Due to its market position, Antonius was one of the first vessel head manufacturers to start working towards NORSOK certification:

When NORSOK was introduced in 1994 we were already experimenting with Forming, welding, formed welds and heat treatments of the products / materials of duplex and super duplex steel. Meeting the requirements of the standard was a logical next step, but there were also some interesting challenges.

Renewing our NORSOK vessel head certification

Similar to other relevant standards, NORSOK certification requires regular renewal. This entails that every five years, Antonius collaborates with Aker Solutions, accredited to assess and certify our compliance with NORSOK, to conduct the necessary tests at our manufacturing facilities in Maasbracht (Netherlands) to renew our manufacturing procedure conformity records (MPCR).

Antonius unique NORSOK certified vessel heads

Antonius is NORSOK certified to work with 3 specific materials and able to perform 3 manufacturing processes with each. The materials are:

  • Duplex (22Cr Duplex SS (UNS S31803 and UNS S32205) according MDS D43 Rev.6)
  • Super Duplex (25Cr Super Duplex SS (UNS S32750) according MDS D53 Rev.6)
  • 6Mo SS (UNS N08926 and UNS S31254, the former for cold pressing, the latter for hot pressing)

The manufacturing processes are:

  • Dishing & Spinning with weld seam before forming
  • Dishing & Spinning seamless
  • Hot pressing seamless

Would you like to know more about our ability to manufacture NORSOK certified vessel heads? Please contact our sales team via sales@antonius.nl or call +31(0)475 439 000. Our engineers are happy to tell you more about our options in terms of manufacturing time, specifications and costs. Our certifications can, of course, be reviewed by visiting our certification page.

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