API 5L steel grades 3

The technical specifications outlined below are stringent
so kindly consider them as a reference only.



1. I would be reluctant to utilize X60-X80 CS pipes
for sour service. Mainly due to their weldability
problems and high tensile strenght values which
makes them prone to SSC. If compelled to
consider thickness reduction in view of PWHT
or value engineering requirements especially for
Hp Gas pipelines; increasing the diameter is a
win-win situation.

2. Chemical Composition, NACE-MR0175 & NACE-TM0284
a)
Restricting, C, S, P, Ca & Ni contents,
limiting the CE to 0.38, Ca/S ratio
to 1.5 of S > 0.0015 and Al:N ratio to
be >= to 2:1

b)
SAW (Spiral) & ERW
I be reluctant to utilize either type of pipes
unless several supplementary requirements are
in place. As an example:

-> Only high frequency for ERW pipes (400+)
and perhaps only Induction Welding
-> Double Hydrostatic testing to examine
pressure reversal phenomena.
-> Diameter reduction test upto 50% at
various orientations without any visible
indications.
-> Pre-Qualify the manufacturers and their
suppliers (mills)

c)
Mechanical Testing

-> Impact Testing (Charpy)
-> Hardness Readings inclusive of (Base, HAZ,
Weldment) perhaps 15 readings across the
wall thickness maximum Hv10 around 180 BHN.
-> Limiting the maximum tensile & yield strenght
-> Stipulating yield to be 85% of the uts.


3. Acceptance criterion for NACE0284
Solution: A

CLR:5% average of 3 sections
CTR:3%
CSR:1.5%

LCT: 0.1mm
TCT: 0.1mm


General:

At least one specimens for each testing method shall be taken from the center of a the pipe or plate.

4. Several other requirements for fittings & flanges (butt
welded, forged)

5. All plates to be supplied normalized and normalizing
is required after Cold Forming, welding, locally
heating fittings.

Cheers

Hi! PVRV.
Can you help me?
it's about pipe API-5L GR.B, if it is possible to be used, in application with high temperature evacuation of liquid hydrocarbon from a stabiliser (liquid at T°= 260 °C).
- When the pipe is at atmospheric temperature (Tmax.= 40 °C ;and Tmin.= 5 °C), so my question is if we can evacuate the hot liquid into this pipe with no risk of rupture (caused by big temperature difference).

- Please, give me some ideas to began my study with this grade of metal ; and What are the conditions we have to consider.

Thank you for your quik reply.

1. High Temperature Service

1.1 API 5L Gr. B, may be utilized with proper
design considerations. Mainly, downgrading
allowable stress. Take a look at ASME Sec. II
Pt. 4 tabulations pretaining to allowable stress
versus temperature for various ferrous materials.

1.2 ANSI B31.3 illustrates the use of governing stress
equation and degradation factor for temperature.

1.3 Take a look at the following CS piping materials
suitable for high temperature service:

A106, A234, A216, A194, etc


2. Thermal Cyclic Stresses/Thermal fatigue/Thermal Shock

Please elborate:

2.1 Operating Pressure
2.2 WeldHead Rating
2.3 Depth/Water Column
2.4 Low/High Bubble Point
2.5 Tubing / Casing production
2.6 etc etc etc

At any rate take a look at API 5CT.

Cheers

Verry helpful reply.
I'll consider all your recommandations. and, I have to rectify for Max. temperature of liquid: 330°C (not 260°C).

At 330 C, it would be prudent to consider alloy material.
Let me know if need some examples.

Hi! PvRV
For CS piping indicated in point 1.3 (your reply); I've foud that A106-B grade is recommanded in API RP 14E when the range of temperture is (30°F to 650°F).
API 5L-B is indicated also but preference is for A106-B, with hogh temperature.

1- Is there big deference between the two grades on economic consideration ?
2- For thermal schok (point 2 in your reply), I've foud in a metallurgical document, that rupture of ordinary CS caused by thermal stress is possible essentially when temperature is greater than 400 °C. So with 330°C; I considere no probleme with a rapide heating of the pipe. What is your opinion ?

1. API 5L Gr. B & A106 Gr. B; from a economic prespective
there isnt much of a difference.

2. Its not a bad idea to consider insulating the
pipeline, avoiding high schedule pipes and
restricting the carbon content.

Cheers

Hello PVRV

I would be very please if you can give some information about pressure reversal, specially for ERW pipe.

Is the any literature about it?
How confidence can I get with two pressure hydrostatic test?

thanks