# How thick is it reasonable for the walls of a steel gas pipeline to be?

The TurkStream project site claims the gas pipeline will use pipes made from 39 millimeters of high-quality carbon manganese steel with additional plastic coatings on both sides. Yes, they claim 39 millimeters (roughly 1,54 inches) of steel walls - that's a whole lot of steel! For comparison, the M41 Walker Bulldog light tank had only 38 mm of armor plating.

Is such wall thickness realistic for an industrial gas pipeline? Why would you need that much steel for a gas pipeline?

• I think the answers cover most of it. The only thing I wanted to add was doing a basic conversion tells you what pressures they're dealing with. 2Km of water = 6,562 ft of water = 2,800+ psi of crush pressure acting on the pipe. (conversion assumes water at 60F, ignoring temperature gradient at depth) Commented Oct 16, 2015 at 20:22

It seems realistic to me. This is an undersea pipeline at depths of over 2 km. The pressure would be considerable at those depths (on the order of 20 MPa or 200 atmospheres). The pipe would need to be thick enough to withstand these (very high) pressures.

The Nord Stream pipeline under the Baltic sea is at depths of up to 210m and uses 1220 mm diameter pipe with a wall thickness ranging from 26.8 to 41 mm. The TurkStream site specifies depths more than 10 times this, but with a pipe diameter of 813 mm. Without doing any calculations that seams reasonable.

Undersea pipelines are known to have wall thicknesses of up to 75mm

• Installation depth and method (J-Lay, S-Lay, Reel Lay), the presence of fatigue sections, sweet vs. sour (corrosive) service, insulation type also impact wall thickness.
– user3371
Commented Oct 15, 2015 at 16:29
• Possible silly question: could they use thinner walls by pressurizing the gas in the pipeline to 20 MPa? Commented Oct 16, 2015 at 6:00
• @immibis they technically could, but they don't because of safety. If for some reason the pipeline is depressurized (say there is suddenly a leak at some point), the whole pipeline would fail catastrophically. Everything installed subsea, even big tanks for separators, must be constructed to easily withstand having atmospheric pressure inside. Source: I've worked on subsea oil/gas processing. Commented Oct 16, 2015 at 7:51
• Given such pressurisation, the shallow depth pipeline sections would need the same strength to contain it (admittedly in tension, not compression) so not much win anyway. Commented Oct 16, 2015 at 13:12

Is such wall thickness realistic for an industrial gas pipeline?

Looking through ASME B36.10M-2004, Welded and Seamless Wrought Pipe, there are plenty of pipes that have thicknesses in that range. For example, 16" diameter, Schedule 160 pipe is 1.594" thick:

This translates to about 40.5mm thickness. As another extreme example, 24" diameter, Schedule 160 pipe is a whopping 2.344" (59.5mm) thick!

As @mg4w says, the pressures at play for some of these pipelines can be enormous, so the pipe wall needs to be commensurately thick to withstand those pressures.

Note that per Section 1 of ASME B36.10M, it "covers the standardization of dimensions of welded and seamless wrought steel pipe for high or low temperatures and pressures." That's not to say that pipe cannot be made with thicknesses outside of the ranges in the standard, which is likely the case for some of these heavy industrial applications.

Why would you need that much steel for a gas pipeline?

Remember that the force on the inside of a pipe is proportional to pressure*diameter. So a large pipe needs to be much thicker than a small pipe for the same pressure.

Because of work conditions of pipe (fluids or gas, lifespan, pressure inside the pipe...), and I think that was calculated by design engineers and the result accordance with application code/standard. For the tank you should not compare like this because work condition and application code/standard not the same. When repairing or maintaining the pipe, it is much more difficult.