Accuracy of PMI

[Pravin Poornachandran]

Dear expert, 

Good day. 

Recently I performed WPS for ER70S-G for nace requirement project. 

Based on welding consumable mill certificate as per EN10204 3.1, Ni <1% and these chemical analysis is conducted in authorised laboratory following the method specified in industrial code. It is laborious procedure and accurate. 

But when we perform PMI, Ni values shows 1.2-1.5, which client is questioning now. 

I did contacted consumable supplier and they are very certain Ni is less than 1%. 

Can anyone advice how should I handle this situation. 

Best regards,

Pravin Poornachandran 

[Jamie Reyes]

Tolerance allowed 

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Regards,

Jamie Reyes

J.R. Machine Company, Inc.

[Raghuram Bathula]

PMI is not for verification of chemical composition just to verify the alloy garde, cross check with wet analysis

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[Vishwas Keskar]

PMI is not giving  any   a chemical analysis .

Do following -

Weld a pad using that lot /heat of consumables .

DO spectro and confirm the chemistry or 

send the wire for Chemical Analysis by Weight Method 

[Jamie Reyes]

MY PMI GUN NITRON XL2 READS Ni%. JUST FINE....

Regards,

Jamie Reyes

J.R. Machine Company, Inc.

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[pgos...@rogers.com]

Hi Pravin,

What method was used, XRF or OES?  XRF will not reveal “C” and other lighter elements, “S”, “P”…

If you have doubtful results with one method , try other.

Often the accuracy will depend on the equipment calibration, cleanliness , number of shots/reading taken and more..

 

Thanks.

 

 

Pradip Goswami.P.Eng, IWE.

Independent  & Consulting Welding & Metallurgical Specialist

Linkedin: https://www.linkedin.com/in/pradip-goswami-2999855/

Email:pgos...@rogers.com,pradip....@gmail.com

Cell/Whasapp:1-905-9793232

 

From: Pravin Poornachandran <htcis...@gmail.com>
Sent: February 2, 2021 10:44 PM
To: 'Bijay' via Materials & Welding <material...@googlegroups.com>
Subject: Accuracy of PMI

 

Dear expert, 

 

Good day. 

 

Recently I performed WPS for ER70S-G for nace requirement project. 

Based on welding consumable mill certificate as per EN10204 3.1, Ni <1% and these chemical analysis is conducted in authorized laboratory following the method specified in industrial code. It is laborious procedure and accurate. 

 

But when we perform PMI, Ni values shows 1.2-1.5, which client is questioning now. 

I did contact consumable supplies and they are very certain Ni is less than 1%. 

 

Can anyone advice how should I handle this situation. 

 

Best regards,

Pravin Poornachandran 

 

Virus-free. www.avg.com

[james gerald]

Dear Pravin,

Normally PMI is performed for High alloy welding consumables to ensure that there is no mix up of consumable during welding and it is not an accurate method and tolerance is always allowed; PMI performed by below methods.

1. X-Ray Fluoroscopy

2. Optical Emission spectrometer

3. Atomic Emission spectrometer

4. Volumetric Analysis (Chemical Analysis).

For carbon steel used for NACE service to ensure Nickel Kept within 1%, we control the issue of welding consumable from the stores. Only welding consumable containing 3.1/3.2 certificate batch Numbers are identified and electrode issue slip from the supervisor to stores will contain the batch Number.

But your case seems to be special since carbon steel is not PMI tested but it is your client requirement and need to be complied.

Moreover it is understood from your mail that you have performed Chemical Analysis (volumetric Analysis) at chemical lab which always gives accurate results.

Below are considered the way forward for your problem.

1. Check the Batch Number to ensure traceability to certificate to ascertain the use of correct welding consumable.

2. Perform proper sampling and redo the test.

3. Perform an Hardness test. The purpose of restricting Nickel is to ensure that it does increase the Hardenability (Hardness).

4. Check whether it is a Specification requirement or Additional client requirement and then take up with the client accordingly.

Thanks & Regards

J.Gerald Jayakumar

[José Juan Jiménez Alejandro]

I want to understand that the PMI was already done on the filler material applied to your component and I also assume that the chemical composition of the filler presented by your supplier obviously does so before the filler is applied, this is what I can understand about your case. I'm going to give my comment based on ASME, because that's what I know:

(1) P + F = A

where:
 P (parental) refers to the P number or classification of the base material.

F (filler) refers to the filler material, that is, your electrode.

A refers to the material already applied to the component

Then the PMI reading of your weld bead will never be the same as the chemical composition of your contribution, this is a fairly common error for not knowing and understanding the formula (1), that's what I can tell you based on what I could understand your problem, since for me it is not clear.
Regards!.

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/1207651108.1303515.1612333837815%40mail.yahoo.com.

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Ing. José Juan Jiménez Alejandro

Independent Consultant in Parts

and Pressure Equipment

SUMMIT MÉXICO - TPI

https://www.linkedin.com/in/summit-m%C3%A9xico-tpi-760047137/

Móvil +52 1 812 352 4606

Skype: jjjimeneza

[sunil kaushik]

PMI is the sorting method .you shoul go for the wet analysis testing.

[Vinay Thattey]

depends on type of equipment , accuracy , calibration done . my practical experience is ... 2 to 3 % variation is possible in PMI 

On Wed, 3 Feb 2021 at 09:17, Pravin Poornachandran <htcis...@gmail.com> wrote:

[Pravin Poornachandran]

Dear expert, 

Truly appreciate all the comments and advise.

It really helps me to understand better on the testing method, chemical analysis and how I can explain to client. 

Indeed it’s client additional requirement which I feel it’s not necessary because supplier has been supplying the same batch to other NACE project as well and there is no such issue at their site. 

Thank you so much experts. 

Best regards, 

Pravin Poornachandran 

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[Rajnish Dixit]

I think many members have already advised any things. I have just to add that please consider the calibration and tolerance for the particular equipment being used and composition of the element(s) respectively.

Thanks,

Best Regards,

Rajnish

Sent from Yahoo Mail on Android

[seejo nereparambil]

Dear All,

Refer to below mail there is small correction * low alloy steel 

Sent from Yahoo Mail on Android

On Sun, 14 Feb 2021 at 10:31, seejo nereparambil

<see...@yahoo.com> wrote:

Dear Experts,

We are in process of Proceedure qualification for CS to Low carbon steel. Hence ,i am seeking your advise to select suitable welding electrodes for  welding between AISI 4130 to API 5L X60 material

Design code is ASME B 31.3 and qualification in accordance with SecIX, thickness is 14.27 mm

Kindly provide your recommendation 

Rregards

Seejo

Sent from Yahoo Mail on Android

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[Prakash Hegde]

Hi!

You can use E10018D3 or E11018D3

Rega4ds

Hegde

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