Thread by @energy_blogger

As #Nordstream pipeline continuous to be exposed to seawater, a quick 50,000ft note on metallurgy

For severe corrosive service like Seawater different grades of steel are used

Many can be confined to 2 types of Stainless Steel

1) Duplex Stainless Steel (SS)
2) Super Duplex SS

In many cases sacrificial elements / coatings are also used to reduce corrosion.

Nord Stream pipeline is one such, a combination of Internal & External Coating.

Hence NS ended up with a FD grade CARBON STEEL pipes, as per DNV OS-F101 (German standard)

#NordStream2

Since outer environment of NS pipeline is corrosive seawater, lot of effort was made to protect exterior pipeline surface and not interior

A 3-layer polyethylene external anticorrosion coating was applied

An additional layer of concrete was coated to remain stable on the seabed

Three External Coating Layers are

• Inner layer: fusion-bonded epoxy
• Middle layer: adhesive
• Outer layer: high-density polyethylene base

Together they form the anti-corrosion coating.

Remember, it is not easy to coat anything on stainless steel unlike Cast Iron / CS

Whereas in contrast to outer 3 layers coating, internal pipeline has a single coating of epoxy base

It’s an antifriction coating to increase flow capacity of the pipeline system.

So the internal coating is not meant to protect pipeline from seawater corrosion. #Nordstream1

Seawater will fill in one section of the pipeline and not complete length

But this section is 100s of Km long in Nord Stream

So the flooded seawater section of pipe is now subjected to something called “pitting corrosion”

It basically creates localized holes on metal's surface

So those sections of pipe should now be exposed to seawater will be beyond repair after few weeks.

Complete section has to be replaced with new pipeline which includes welding every 12 m (~40ft).

And to complicate matters, NS had sourced pipe & valves from Germany & Italy.

They were the only suppliers who could qualify from this entire planet!!

So in case Russians have to carry out repair work, they need to buy pipes from Italy and don’t think sanctions would allow it

So my conclusion it is going to take a very long time for NordStream to come back.

Until sections of pipe are not secluded quickly, it is going impact months if not in years.

#NordStreamSabotage #OOTT

This picture with average human size comparison against valve installed in Nord Stream onshore sections.

Hopefully gives the perception on size of things we are discussing.

Design Operating Conditions of #Nordstream pipeline.

Pipeline illustration and some of the details are taken from NS website. Link given below

nord-stream.com/download/docum…

Pitting Corrosion Image:
researchgate.net/figure/Pitting…

DNV *Norwegian standard!

Adding the picture of coatings to my thread. Thanks to Leo Lenox