Lamination defects in Amm piping
Lamination defects in Amm piping
(OP)
We have a low temp CS pipeline carrying liquid ammonia at minus 33 Deg, these pipes were found with "lamination defects" which were considered to be acceptable from design view point. These defects were marked on the pipelines and need to be monitored for their growth on regular intervals form outside. We had initially welded some probles along these defects and had measured the growth using LCPD technique. It seems the LCPD doesnt work and we need to resort to some other technique, all other NDT methods such UT or MPI are not suitable as these require insulation removal which is not possible beacuse of sub zero temperature of medium. Does any one know about a suitable NDT method that can be employed to monitor these defects.
regards
regards





RE: Lamination defects in Amm piping
"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)
RE: Lamination defects in Amm piping
What US/ISO/DIN/API specification was used to purchase the piping ?
It has been my experience that all of these piping specifications require a metalurgical process ensuring a "fully killed steel" that is specifically designed to prevent these defects.
These are very serious defects that prevent the full range of forces and moments to be transmitted through the pipe wall. Unwanted shear stresses can be developed between the laminations.
While some structural plate components can be used with laminations (e.g. steel column baseplates loaded in compression only)....piping is a whole 'nother matter.
I suggest that you re-post your question in a metalurgical forum
My opinion only...
-MJC
RE: Lamination defects in Amm piping
In the US, ASTM standards require "fully killed" steels for all wrought ferritic components:
http://www.astm.org/Standards/A960.htm
This Chemical engineering "rules of thumb" document seems to require a "fully-killed" construction (i.e. no laminations) for piping in low temperature service:
http://b
Remarks or comments ?
RE: Lamination defects in Amm piping
I was going to suggest RT, but it is a liquid product inside the line, you might be able to get shots if you shut the line down temporarily, if these indications have depth to them you might be able to see them with RT.
Can you just put sleeves over these affected areas?
If these are simply surface breaking laminations I am not seeing an issue... it is the mid-wall non-planar laminations I would be concerned about.
Have you ever recorded growth on any of these?
I am a little ignorant of liquid ammonia and integrity concerns associated with it, normal gas/oil/water lines contain laminations in pratically every joint, both external and internal.
RE: Lamination defects in Amm piping
Lamination discontinuities are and were quite common in "killed", ingot cast steels without desulfurization and sulfide shape control melting practices. Laminations were often found in welded pipe fabricated from plate.
RE: Lamination defects in Amm piping
During construction, the line was fitted with probes and connecting cables were taken out through insulation to measure the growth using ACFM method. (You can read more ACFM on htt
RE: Lamination defects in Amm piping
"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)
RE: Lamination defects in Amm piping
"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)
RE: Lamination defects in Amm piping
RE: Lamination defects in Amm piping
You state:
"Lamination discontinuities are and were quite common in "killed", ingot cast steels without desulfurization and sulfide shape control melting practices. Laminations were often found in welded pipe fabricated from plate."
What are the ASTM/API or other testing standards the quantify the limits on laminations within plate-fabricated pipe ?
How is this to be controlled when virtually all pipe is purchased on the internaltional market ?
Regards
-MJC
RE: Lamination defects in Amm piping
Depending on your needs, you may wish to order welded API-5LX, A-671 or A672 pipe with UT performed on the plate/skelp per A-578. You can always order low sulfur steel.
Just of note; we recently received some ASME Section I pipe spools fabricated from A106 B seamless pipe made in Poland that had some highly anamolous, severe linear discontinuities that could have been found with either Magnetic Testing or Shear Wave UT. After determining severity we scrapped the pipe spools. Quite frankly, I have never seen anything quite like it in my 40 years; only pictures would suffice but I have none. But that's the global market place. If mthakurs' pipe flaws were similar, I would recommend replacement at soonest oportunity.
RE: Lamination defects in Amm piping
RE: Lamination defects in Amm piping
RE: Lamination defects in Amm piping
RE: Lamination defects in Amm piping
RE: Lamination defects in Amm piping
RE: Lamination defects in Amm piping
Tent and flood it with dry warm air if you have to.
"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization