DNV Fabrication and Testing of Offshore
Structures

DNV -OS-C401 offshore construction standards contain technical requirements, principles and acceptance criteria related
to classification of offshore units as it pertains to DNV/GL classification society. Order your copy here:

https://global.ihs.com/doc_detail.cfm?document_name=DNV%2DOS%2DC401&item_s_key=00398859

This standard will:
— Provide an internationally acceptable standard giving the minimum requirements for fabrication of
offshore structures, installations and equipment by welding, including requirements for mechanical fastening,
testing and corrosion protection systems.
— Provide guidelines for designers, fabricators, manufacturers, suppliers, purchasers and regulators.

This DNV standard is written for world-wide application. Note: Country and local government jurisdiction regulations may
include requirements in excess of the provisions by this standard depending on the size, type, location and
intended service of an offshore unit.

The standard provides requirements for fabrication and testing of offshore units.
The standard gives requirements for the following:
— Contractors: Chapter Two – Section Two
— Welder qualifications: Chapter Two – Section Three
— Welding consumables: Chapter Two – Section Four.
— Qualifying weld procedures: Chapter Two – Section Five
— Tolerances: Chapter Two – Section Six
— ND testing: Chapter Two – Section Seven
— Coating and Corrosion Protection systems: Chapter Two – Section Nine
— Mechanical fastening: Chapter Two – Section Ten

Also included are the DNV’s recommendations on safe engineering practices for general use by the
offshore industry.

The requirements in this standard apply to offshore units, installations and equipment fabricated by
welding.

DNV Certification – It Matters

Let us get your project DNV Certified… “missing metal studs in some sections of the structure, different kinds of concrete used for the slab and unfinished or badly welded joints were some of the other factors that caused the raised railway to buckle, sending two subway carriages plummeting to the streets below.”

https://amp.cnn.com/cnn/2021/06/16/americas/mexico-city-subway-collapse-investigation-intl-latam/index.html

Do You Need The Precision of Laser Cutting?

Maybe not – a neighbor just asked me:

Tube Laser Cutting Houston, Texas

“I am in need of a 1/4  plate of cast iron measuring about 30” x 24” for a fire back in my fire pit (to radiate heat)  Do you know someone locally that might carry this or could cut to size?”

My answer: Try to find a local metal fabricator with a plasma cutting table. The problem will be finding someone who will do a small job like that. You might have to be flexible on turn around time, allowing them to “fit it in” between their higher production jobs. FYI – you don’t want cast, you want “plate” metal. Cast metal is just that, casted to a specific size in a mold and no one cuts, or provides that. You want just plain old carbon steel plate (most common is A36)

ALSO –   fire will burn through / rust through any metal. I would have them cut it out of 3/8″ or 1/2″ would be even better. The material cost will be the least expensive part of this job. Many shops also have minimum order sizes ranging from $100 to $300 – hopefully you can find one that will work with you. Plasma cutters are fairly common these days and the “edge quality” has really improved. Ask the about edge quality. While you can’t expect baby butt smooth (like we get on our lasers) – you also don’t want it to look like they cut it with a oxy/acetylene torch. So steer clear of oxy/acetylene cutting tables, or anyone offering to cut it by hand with a torch, unless you don’t care if it has ragged edges… We only do laser cutting. But you do not need that kind of precision.

High definition” plasma cutting tables are the latest and greatest. But any plasma cutter should meet your needs. Most “metal fabrication” shops in Texas have added a plasma cutting table to their service offerings, you can find a metal fabricator on every corner in Houston!

Houston, TX DNV Fabrication 2.7-1 & 2.7-3 for Offshore Lifting Equipment

houston-dnv-fabrication-2.7-1-2.7-3
Houston, TX DNV Fabrication 2.7-1 & 2.7-3 for Offshore Lifting Equipment

DNV Fabrication Certified for Lifting Equipment. DNV GL 2.7-1 and 2.7-3 are offshore fabrication certifications specifically for lifting operations while the vessel is stationary or under way.

DNV Umbilical Spools – DNV Lifting Baskets  – DNV Equipment Skids

We can fabricate any structure and any equipment to any DNV specification.

For a Complete “How To” on the DNV fabrication process, please see our explanation here: https://oceanfabricators.com/how-to-fabrication-of-dnv-certified-skids-2-7-1/