@LittleInch - drawings wont be able to share due to proprietary issues. But got yr point.
@ironic metallurgist & r6155: the main concern I find is that the packing/pads used to fix scaffolding inside the vessel should not mask a leak in the vessel. also, scaffolding pipes are hollow, not sure...
Dear friends,
one of our fabricator is insisting on conducting hydrotest on a vessel at shop (designed to ASME Sec VIII), with scaffolding fixed inside. they do not intend to remove the scaffolding.
Can someone throw some clarity on this, how decision to be taken OR pros & cons be established
Hello Friends
We have a specification that calls for a BOND STRENGTH in cladded (2-14 Cr + SS347) plate. The clause states that the "Stainless Steel Bond Strength shall be at the upper yield strength at the low end, and approaching the UTS at the high end"
Now i am feeling confused, since as...
Hello
in my opinion, RT is not feasible/in-effective in this kind of joint. UT is partially feasible/effective, that too only with correct combination of angle probes. Still UT may be specified in the specification.
I would recommend MT in this type of weld.
Shashank
ASME Sec VIII Div-1, UW-13-e should be your clause of reference.. read it, repeat it, till you understand each word. These end joints are very critical in nature and if not done with due care and in compliance to all directives of the code, things can go seriously wrong.
Once finning is done, I dont see any importance of hardness difference. The more relevant checks for such resistance welded finned tubes are:
a. Depth of fusion in% of tune thickness.
b. Pull out strength.
c. Hardness with a maximum limit (not the differential values)
d. Fusion.
e. Micro &...
A golden joint is with a exception to hydrotest.. so for the specific valve joints identified already as golden joints, what you intend to propose is already being done.. need more elaboration in your question if I couldn't get it right.
If the petals forming process does not subject the material to a %fibre elongation more than that specified in UCS79, then indeed the above proposal should be accepted. However, you must see the user/licensors specs, in case they have specified something more conservative than this approach...
Friends
Thanks a lot for your contribution and inputs. I extended the discussion with known fabricators in India. Everyone does face this problem on daily basis. Few reasons and solutions they recommend are as under:
Reasons:
a. Higher currents.
b. Current flow in single direction.
c. Direction...
I would suggest you to read through a few articles of ASM manual on welding to get a hint and details of how HAZ behaves and how the same can be restricted, or expanded, by temperatures of preheat/pre-heat maintenance, etc.
Indeed it remains to be the most sensitive part of the weldmment, which...
@0707 : the videos are for demagnetisation.. the particular concern is the Magnetisation & how does that get induced during fabrication & weld overlays by ESSC
Dear Friends
Few years back I faced a peculiar problem in few pressure vessels, where we found that Pressure vessels have become magnetic after fabrication - all these pressure vessels were Weld overlaid & a couple of them were Heat Exchangers.
The metallurgy of the equipments was LAS-2-1/4...
from the discussions, few things i can make out. In my experience, elimination approach is the best to work towards root cause:
1. There are pits waiting to leak - possibility that pits are available before use too - pits which are breeding ground for corrosion.
2. Doesn't look like MIC, but...
Thanks @Don56. However, as per UW42, such weld restoration is only allowed for strength and modification purpose. Therefore the confusion.
Construction in which deposits of weld metal are applied to the surface of base metal for the purpose of restoring the thickness of the base metal for...
As per UW-42, is it permissible to restore a dished head thickness falling below the minimum required thickness?
One of my fabricator has deposited the welding as per UW-42 onknucle of an ellipsoidal head The min req. thickness was 10mm, but observed was 9.6mm.
Any input would be highly...
+3,+6 are clearly notations for corrosion allowance. based on relative corrosion on both sides. Though I am highly surprised - As such,if tubesheet and tubes are supposed to be superduplex 2507 (generic alloy nomenclature), why not channel side is either solid superduplex OR CS +3mm superduplex...
I don't know why i am not able to find an input I was expecting from so many people who have posted above. Actually such field hydro-test technique is quite common in practice.
There is no harm in doing a field hydro-test using limpet coil, i.e., a half pipe welded inside the vessel on the...
