N80 AS A LINE PIPE 1

[Jadson]

Has anybody ever use the N80 or other API 5CT one to use as a line pipe? It´s possible?
I need a material that resist 15000psi at 400°F. There aren´t materials listed in ASME B31.3 (table A1 or table k1) that results in acceptable thicknesses.Does anyone have a sugestion?

 

[LittleInch]

The issue with casing pipe and drill tube is that you can't weld them.

What size and how long. Normally you don't want more than a few metres at most.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

You also need a material suitable for the contents. What's it carrying?
You also need a material suitable for its environment. Installed where?

 

[blacksmith37]

The chemistry is not intended to be weldable ; and traditional N -80 is the most unweldable. It is the highest strength that can be made without quench and temper so high carbon and manganese gave it strength as it air cooled. You could use it as thread and coupled. However in the last 30 + years ,control rolled / micro alloy ( such as niobium) have made ERW products available that are relatively weldable , but they totally depend on what mill you get them from . I mention this because you may have heard someone welded N-80 ; if so it was an ERW micro-alloyed steel .

 

[SJones]

If you are working with an SMYS of 550 MPa, what's wrong with API Spec 5L, L555/X80?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[Jadson]

Thanks for all the replies.

We are designing a process plant, which the following are the main design conditions:

Pressure disign: 15000psi
Temperature of system: 0°C (32°F) and 200°C (400°F)
Fluids: Water and Nitrogen.
Estimated quantity: 2000m

I had selected the X70 and the X80, but to use them there is a temperature limit, as you can see:

I tried to use the table A-1 , but the allowable stress are much less.

Using the information in table A-1, the following are the required thicknesses for specifics OD:
API 5L X70
- OD 101,6mm -> thick 26mm;
- OD 168,3mm -> thick 42 mm;
- OD 273,1mm -> thick 68 mm.

API 5L X80
- OD 101,6mm -> thick 20mm;
- OD 168,3mm -> thick 33 mm;
- OD 273,1mm -> thick 51 mm.


So, these are not commercial. An alternative is to use N80, due to its high Strength Yield. The following are the required thicknesses for specifics OD:

API 5CT N80
- OD 73mm -> thick 14 mm;
- OD 114,3mm -> 17,10 mm;
- OD 219,1mm -> 32 mm;

Note: The diameters are different because I first calculated using ID and then Commercial OD.

Therefore, I need to know more about the weldability of the N80 and its mechanical behavior at 400 ° F.
I will be very grateful if someone gives me a suggestion.

 

[jojoyohan]

B31.3 2018 has allowable stresses for API 5L X70 and X80 to 400 °F in Table K-1.

At 150000 psi, relatively large sizes for that pressure, and above ambient temperature, it is not exactly surprising that you cannot use a commercially available pipe size and will need to have your piping and fittings custom built.

 

[LittleInch]

Jadson,

If you're designing a process plant for fluids with 15,000 psi rating you must first determine which design code you plan to use.

Your snap shots indicate B31.3 and you would appear to be into Chapter IX, Appendix K territory at that pressure and temperature.

The version I have (B31.3 2018) has a different table at K-1 - If you use those values I think you'll be close to the N80 values or maybe even a bit less.

But I cannot find Casing pipe / N80 anywhere in B31.3, so I'm puzzled as to how you have calculated your thicknesses.

It is a little worrying that you seem to be trying to design a plant with such high pressures, but don't appear to understand the basics of piping design or even have the latest version of the code.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[danschwind]

Could you please clarify what you are "processing" that you need 1000 barg of water and nitrogen?

Daniel
Rio de Janeiro - Brazil

 

[Jadson]

Thanks for all the replies.

jojoyohan, you´re right, maybe I have to use piping and fittings custom built.

LittleInch, thank you. The version I have is B31.3 2016. I am trying to request the latest version for my company. However, in any version, ASME B31.3 allows the use of unlisted materials, as long as the requirements it requests are followed.

 

[LittleInch]

Jadson,

Indeed it does allow that, but you then need to obtain the reduction in yield at 400F for your material.

At ambient X80 is 2/3 of SMYS. I can't seen N80 being much better and hence why use it?

At 15Kpsi, you're into API 6A flanges though so you need non ASME B 36.10 pipe sizes if you have any flanged components.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EdStainless]

For high pressure service I have supplied PH Stainless pipe, with 15-5PH being the prefered grade (better transverse properties than 17-4PH).
It was supplied in the overaged condition, then bent and welded, solution annealed, and aged to the final condition (H1050, any harder and the toughness drops). These sections were then bolted together with flanged connections.
Expensive, yes. Bullit proof, damn near. One system was designed for 40ksi service.
Remember to check toughness at low temp also.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed