Welding Overlay - Deposition Rate / Weight Claculation

[JIPMKWA]

Good morning ,


We are looking at repairing a 5' x 5' area of metallizing by sandblasting , grinding and then welding ( .035" dia. - 309SS LSi using Pulsed GMAW). The tube's are 1.250" o.d x .220" m.w SA-213-T11 on 1.50" center's. We have an overlay requirement of .070" minimum to .125" maximum with a 21% as deposited chromium content and a 10% as deposited nickel content. I have been researching how to calculate welding consumable consumptions and had a few questions pertaining to it.

First step - area : 5' x 5' = 25 square feet

2nd step - volume : I figured halfway between .070 and .125 = .0975 . 5 x 5 = x12 = 3600 square inches x .0975 = 351 cu.in..

3rd step - deposited weight : stainless steel has a density of .29 lbs per cu.in. 351 x .29 = 101.79 lbs

4th step - Filler metal required : Deposited weight / Deposition efficiency. GMAW has an efficiency of .96% so 101.79 / .96 = 106.03 lbs

If the welding wire has a 23-25% Cr content and a 12-14% nickel content , should I worry about the base material ( 1 1/4% Cr. ) diluting the weld down past our as deposited requirements. How would I even check ? From what I was told , a P.M.I requires the surface to be completely flat and even then, you would not be able to take any readings on the sides of the tubes - only on the crown.

Also we have a tolerance of maintaining wall alignment to within 1" per 20'. From what I have seen in most boilers, the water walls are usually warped to begin with. How can we possible control warpage ? Is there a basic calculation for how many joules per inch are permitted for a certain thickness of base material per minute ?

What is the best way - fast and accurate for spot checking weld overlay thickness to make sure we are within tolerance ? A friend suggested an Elcometer but I am not familiar with them. U.T thickness readings would require us to take a before measurement ,map it on a drawing , take a final measurement and do the math ? Is there a better way ?




Thank you for your time, I have little to no experience on weld overlay.

 

[metengr]

First, you make no mention of qualifying the above corrosion resistant weld overlay. I would strongly recommend you follow ASME B&PV Code, Section IX for weld procedure qualification of corrosion resistant weld overlay (CRO). Once you qualify the procedure per Section IX (QW-256.1), all your questions should be answered.

 

[PMCap]

Perhaps the below may be of some help in providing cost savings in resolving your issue:

Restoration by encapsulation without removal of the degraded area is not prohibited by the NBIC per Interpretation 04-01.

Restoration hardware forms new ASME Code pressure boundary.

This method of restoration can be very cost effective as the degraded area does not have to be removed thus saving fit-up, welding, and examination installation time and avoiding entry of foreign matter into the vessel.

The Encapsulation component attachment weld is typically classified as an ASME Category D weld that would not require volumetric examinations.

The AI has the authority to waive the hydrostatic pressure test.

Typically, a liquid penetrant or magnetic particle examination is performed on the root and final pass of the full penetration encapsulation to shell attachment weld. See NBIC Interpretations 98-33 and 98-38.

Alternatively, the encapsulation component can be supplied with a pressure port for local pressure testing – see NBIC Interpretation 01-15

The encapsulation component of very low height (typically 1 1/4") can be lined with or constructed entirely out of corrosion resistant material

I suggest you search the internet using the keywords such as - degraded shell restoration by encapsulation

Let me now if you need any further help on this method of restoration for which I am extremely familiar