Heat In Put Calculation for Impact Tested WPS (ASME Sec. IX)

[Babur Khan]

Hello, Dear Expert,
I would appreciate your insights on the following question concerning heat input calculations for impact-tested WPS. The Qualification Code is ASME Sec. IX. Yes, there is an impact test. The contractor has submitted the WPS heat input, which is shown in the screenshot below. (The second last and last columns were added by me.

Question: How do you calculate heat input?

1. Third Last Column: The contractor recorded the highest heat input from PQR on the WPS as it is.
2. Second Last Column: Heat input is computed by averaging the amperage, voltage, and travel speed.
3. Last Column: The calculation of heat input relies on the maximum amperage, voltage, and travel speed.

Which method is the correct one for calculating heat input?

Heat Input will be higher than from PQR with available variables. 

Reference : 

Table QW-253 Welding Variables Procedure Specifications (WPS) — Shielded Metal-Arc Welding (SMAW)

QW-409.1 Increase in heat input shall be consdire essential variable.

QW-409.1 An increase in heat input, or an increase in volume of weld metal deposited per unit length of weld, for each process recorded on the PQR. For arc welding, the increase shall be determined by (a), (b), or (c) for non-waveform controlled welding, or by (b) or (c) for waveform controlled welding. See Nonmandatory Appendix H. For low-power density laser beam welding (LLBW), the
increase shall be determined by (d).
(a) Heat Input 

heat input J/in. (J/mm) = [(voltage × amperage  × 60) / travel speed ] in./min (mm/min)

(b) Volume. Volume of weld metal measured by
(1) an increase in bead size (width × thickness), or
(2) a decrease in the length of the weld bead per unit length of electrode
(c) Heat Input Determined Using Instantaneous Energy or Power

Best Regards,

Muhammad Babur Khan Lashari

Project Quality Supervisor.

API 570, API 510, CSWIP 3.2.2. ISO 9001:2015.

Inspection Department
Mob: +966 58 2774568 / +966 51 0559680

          +92 334 6186285

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[james gerald]

Hi,

There are some noticeable portions in your below table for Heat Input.

1. Your contractor has provided average Heat Input but according to ASME Sec.IX , it is the maximum Heat Input.

2. In your Cap pass, Heat Input is very High since for cap pass you use 2.5mm electrode and the Travel speed will be relatively faster and the allowable Current ranges for 2.5mm electrodes as provided welding consumable manufacturer may not be in this limit.

For GTAW & SMAW  process, the code ASME Sec,IX provides the below formula.

Ways for representation of  Heat Input for each Pass (RooT, Hot/cold, Fill & Cap passes). You can use a Portable arc monitor (PAM) unit to measure Heat Input or use Tong tester for measuring Current & voltage and stop watch to measure Travel Speed. When charpy tests are required Heat Input is a supplementary essential variable.

Way 1

As per ASME Sec,IX, you can mention only the maximum limit of the Heat Input for ach pass no minimum limit applies.

Way2 

For calculation of the minimum Heat using ASME formula above as below

Heat Input (maximum) Current (max) x Voltage(max) x 60 / Travel speed (minimum)

Heat Input (minimum)   Current (min) x Voltage (min) x 60 / Travel speed (max)

WAY 3

Some specification may call for Average Heat Input with allowance of +/- 10%, for that calculate Heat Input average for each pass and minimum Heat Input with 90% & maximum Heat Input 110% and that will be the range. For this way you have to calculate for each pass Heat Input & measurement. and calculate the average

Thanks & Regards

J.Gerald Jayakumar

0091-8838619635

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