Arc welding, cutting and spraying activities: guide to reporting

This document outlines the steps that facilities with welding, cutting and spraying activities should follow to report to the National Pollutant Release Inventory (NPRI).

Download the Arc welding, cutting and spraying calculator to help you estimate the releases of National Pollutant Release Inventory (NPRI) substances.

Background information

The main NPRI substances used in the arc welding, cutting and spraying processes are Part 1A metals (for example, chromium, cobalt, manganese, nickel) and Part 1B metals (for example, hexavalent chromium, lead). Part 4 substances – Criteria Air Contaminants (CACs) – are also released during the welding, cutting and spraying processes. The main CACs of concern are total particulate matter (TPM), particulate matter less than or equal to 10 microns in diameter (PM10) and particulate matter less than or equal to 2.5 microns in diameter (PM2.5).

Categories of arc welding, cutting and spraying processes in Canada

One of the categories of arc welding processes found in Canada is consumable electrode arc welding processes. Examples of this type of process include:

Welding rods and wire are similar and are considered consumable electrodes.

The other category of arc welding processes in Canada is non-consumable electrode arc welding processes. This category includes:

Examples of cutting processes include:

Examples of spraying processes include:

The remainder of this guidance document will be focused on the reporting requirements related to arc welding, cutting and spraying processes.

Please note that soldering activities are not considered to be a welding operation, although NPRI reporting still applies to them.

Reporting on arc welding, cutting and spraying processes

Threshold calculations

You need to consider the NPRI substances associated with arc welding, cutting and spraying activities occurring at your facility when you perform threshold calculations.

In order to correctly perform threshold calculations for arc welding, cutting and spraying activities, you need to understand the term "article".

An "article" is defined as a manufactured item that does not release an NPRI substance when it undergoes processing or any other use. When an article is processed and there are no releases, or the releases are recycled 100% with due care, the NPRI substances in that article need not be included in the threshold calculation.

Parts 1 A and B metals

You can use these points to determine which sources of NPRI substances need to be considered in your threshold calculations.

Notes:

  1. The base metal being welded or sprayed retains article status. As such, all NPRI-listed substances found in the base metal do not have to be considered in your threshold calculation for arc welding and spraying activities.
  2. With the exception of the reciprocating saw process, the base metals being cut by any of other the cutting processes (included in the arc welding, cutting and spraying calculator) lose their article status.

Using the arc welding, cutting and spraying calculator

After you have completed your threshold calculations and compared the total amounts MPO to the reporting threshold, you must then calculate the released, recycled and disposed values for those substances that meet or exceed the reporting threshold.

The arc welding, cutting and spraying calculator considers six different types of  arc welding processes and various welding electrode or rod/wire types; five types of spraying processes; and seven types of cutting processes. The spreadsheet calculator is the preferred method of calculation.

Arc welding process sub-categories:

Spraying process sub-categories:
Cutting process sub-categories:

Calculating emissions for “other” types of processes/electrodes

There are limited or no data available on emission factors for some processes/electrodes. To address this, some emission factors have been suggested in arc welding, cutting and spraying calculator for “other” types of processes/electrodes.

In the absence of supporting data, the emission factors for “other” types of processes/electrodes have been obtained by averaging the known and non-zero emission factors of the similar category.

For example, the PM10 emission factor for “other SMAW electrodes” is an arithmetic average of all known PM10 emission factors of SMAW electrodes . This approach ensures that the PM10 emission factor for “other SMAW electrodes” is in the range of known SMAW PM10 emission factors.  

If the arc welding type is listed in the calculator but the specific electrode/filler material is unknown or not listed, you can use the following according to the welding type:

If the specific type of welding is unknown or is different than SMAW, GMAW, FCAW, SAW, GTAW, or PAW, you can use the input field for “Other Arc Welding Methods”.

If the specific type of cutting or spraying process is unknown or not listed, you can use the input field for “Other Cutting Methods” or “Other Spraying Methods,” respectively.

The suggested emission factors for “other” types of processes/electrodes should only be used if there are no site-specific estimation method available for activities at your facility. Contact the NPRI HelpDesk if you have questions.

Please note: The arc welding, cutting and spraying calculator should not be used for mechanical/cold cutting methods (for example, press cutting) that have not been specified in the calculator.

Active cutting hours

For cutting processes, annual active cutting hours (hours/year) are required as an input for the calculator. Active cutting refers to the time that the material is being cut. You also have to calculate the time-averaged mass fraction for each of the following elements for all materials that went through cutting:

The time-averaged mass fraction should be calculated separately for each cutting process.

For spraying processes, the annual amount (kg/year) of material sprayed is required as an input for the calculator. The base metal being sprayed retains article status. You have to calculate the weight-averaged mass fraction for the following elements over all sprayed materials:

The weight-averaged mass fraction should be calculated separately for each spraying process.

Example one: arc welding calculation

Let’s assume the following for our example:

Step One: Determine the amount of manganese (a Part 1A substance) MPO and compare it to the 10-tonne reporting threshold. If it is greater than the 10-tonne threshold, calculate the amount of manganese released due to the welding process.

Remember: When using an arc welding process, the base metal being welded retains its article status. Therefore, it does not need to be considered in either the threshold or release calculations.

The amount of MPO can be calculated using the following equation:

Amount of manganese = Amount of welding rod used [tonnes] x (weight percent manganese in welding/100%)
= 1,000 tonnes x (1.3%/100%)
= 13 tonnes of manganese

Since the amount of manganese is greater than the 10-tonne reporting threshold, your facility must submit a manganese substance report. In this example, we assumed that no manganese is recycled or disposed, but that some manganese is released as a result of the welding activity. As a result, the release estimate must be completed.

The arc welding, cutting and spraying calculator will automatically calculate the releases for all relevant substances once you enter the rod usage amount.

The amount of manganese released can be calculated using the following equation:

Manganese released [tonnes] = Amount of welding rod used [kg] x emission factor [kg Mn released/kg welding rod used] x [1 tonne/1,000 kg]
= 1,000 [tonnes] welding rod used x 1,000 [kg/tonne] x 0.0022 [kg Mn released/kg welding rod used] x 0.001 [tonnes/kg]
= 2.2 tonnes manganese released

Based on the above, you would report 2.2 tonnes of manganese to the NPRI for the reporting year as a result of the welding activities occurring onsite. In this case, it would be reported as a release to air. Note that since the reporting threshold was satisfied for manganese, you must now report for all manganese that was released, recycled or disposed.

Step Two: Determine the amount of PM10 released from the welding process. As mentioned above, the arc welding, cutting and spraying calculator will automatically calculate the releases for all applicable substances once you enter the rod usage amount.

The amount of PM10 released can be calculated using the following equation:

PM10 released [tonnes] = Amount of welding rod used [kg] x emission factor [kg PM10 released/kg welding rod used] x 0.001 [tonne/kg]
= 1,000 [tonnes] welding rod used x 1,000 [kg/tonne] x 0.0151 [kg PM10 released/kg welding rod used] x 0.001 [tonne/kg]
= 15.1 tonnes PM10 released

The reporting threshold for PM10 is 0.5 tonnes released to air. Since the release value for this example is 15.1 tonnes, a substance report is required for PM10. As well, you must add all other PM10 releases at the facility to the 15.1 tonnes. You must report the resulting value to the NPRI.

Example two: spraying calculation

Let’s assume the following for our example:

Step One: Determine the amount of nickel (a Part 1A substance) MPO and compare it to the 10-tonne reporting threshold. If it is greater than the 10-tonne threshold, calculate the amount of nickel released due to the spraying process.

Remember: When using a spraying process, the base metal retains its article status. Therefore, it does not need to be considered in either the threshold or release calculations.

The amount of MPO can be calculated using the following equation:

Amount of nickel = Amount of spraying material used [tonnes] x (weight percent nickel in the spraying material/100%)
= 100 tonnes x (25%/100%)
= 25 tonnes of nickel

Since the amount of nickel is greater than the 10-tonne reporting threshold, your facility must submit a nickel substance report. In this example, we assumed that no nickel is recycled or disposed, but that some nickel is released as a result of the spray welding activity. As a result, the release estimate must be completed.

The arc welding, cutting and spraying calculator will automatically calculate the releases for all relevant substances once you enter the required input information.

The amount of nickel released can be calculated using the following equation:

Nickel released [tonnes] = Amount of spraying material used [kg] x (weight percent nickel in the spraying material/100%) x emission factor [g nickel released/kg nickel sprayed] x 0.000001 [tonne/g]
= 100 [tonnes] spraying material used x 1,000 [kg/tonne] x (25%/100%) x 150 [g nickel released/kg nickel sprayed] x 0.000001 [tonne/g]
= 3.75 tonnes nickel released

Based on the above, you would report 3.75 tonnes of nickel to the NPRI for the reporting year as a result of the spraying activities occurring onsite. In this case, it would be reported as a release to air. Note that since the reporting threshold was satisfied for nickel, you must now report for all nickel that was released, recycled or disposed.

Step Two: Determine the amount of PM10 released from the spraying process. As mentioned above, the arc welding, cutting and spraying calculator will automatically calculate the releases for all applicable substances once you enter the required input information.

The amount of PM10 released can be calculated using the following equation:

PM10 released [tonnes] = Amount of spraying material used [kg] x emission factor [g PM10 released/kg spraying material used] x 0.000001 [tonne/g]
= 100 [tonnes] spraying material used x 1,000 [kg/tonne] x 60 [g PM10 released/kg spraying material used] x 0.000001 [tonne/kg]
= 6 tonnes PM10 released

The reporting threshold for PM10 is 0.5 tonnes released to air. Since the release value for this example is 6 tonnes, a substance report is required for PM10. As well, you must add all other PM10 releases at the facility to the 6 tonnes. You must report the resulting value to the NPRI.

Example three: cutting calculation

Let’s assume the following for our example:

Step One: Determine the amount of copper (a Part 1A substance) MPO and compare it to the 10-tonne reporting threshold. If it is greater than the 10-tonne threshold, calculate the amount of copper released due to the cutting process.

Remember: When using an oxy cutting process, the base metal being cut revokes its article status. Therefore, it needs to be considered in either the threshold or release calculations.

The amount of MPO can be calculated using the following equation:

Amount of copper in material A= Amount of material A [tonnes] x (weight percent copper in Material A /100%)
= 50 tonnes x (20.0%/100%)
= 10 tonnes of copper

Amount of copper in material B= Amount of material B [tonnes] x (weight percent copper in Material B /100%)
= 100 tonnes x (40.0%/100%)
= 40 tonnes of copper

Amount of copper = Amount of copper in Material A + Amount of copper in material B
=50 tonnes of copper

Since the total amount of copper is greater than the 10-tonne reporting threshold, your facility must submit a copper substance report. In this example, we assumed that no copper is recycled or disposed, but that some copper is released as a result of the cutting activity. As a result, the release estimate must be completed.

The time-averaged mass fraction of cobalt for oxy cutting can be calculated using the following equation:

Total active oxy cutting hours = Time spent for material A [hours] + Time spent for material B [hours]
= 1,000 hours + 2,000 hours
= 3,000 hours

Time-averaged mass fraction of copper for oxy cutting = (Time spent for material A [hours] x (weight percent copper in material A/100%) + Time spent for material B [hours] x (weight percent copper in material B/100%)) / (Total active oxy cutting hours [hours])

= (1,000 hours x (20.0%/100%) + 2,000 hours x (40.0%/100%)) / (3,000 hours)
= 0.333

The total active oxy cutting hours and time-averaged mass fraction of copper should be entered in the calculator for the oxy cutting process.

The arc welding, cutting and spraying calculator will automatically calculate the releases for all relevant substances once you enter the required input information.

The amount of copper released can be calculated after determining the amount of TPM released from the oxy cutting process. In the arc welding, cutting and spraying calculator, all PM10 emissions are assumed to be the same as TPM.

The amount of PM10 released can be calculated using the following equation.

PM10 released [tonnes] = Total active oxy cutting hours [hours] x (60 min/1 hour) x emission factor [g PM10 released/min of cutting] x 0.000001 [tonne/g]
= 3,000 [hours] x 60 [min/hour] x 0.38 [g PM10 released/ min of cutting] x 0.000001 [tonne/g]
= 0.068 tonnes PM10 released

The amount of copper released can be calculated using the following equation:

Copper released from oxy cutting process [tonnes] = Amount of TPM released from oxy cutting [tonnes] x Time-averaged mass fraction of copper for oxy cutting
= 0.068 [tonnes] x 0.333
= 0.023 tonnes copper released

Based on the above, you would report 0.023 tonnes of copper to the NPRI for the reporting year as a result of the cutting activities occurring onsite. In this case, it would be reported as a release to air. Note that since the reporting threshold was satisfied for copper, you must now report for all copper that was released, recycled or disposed.

The reporting threshold for PM10 is 0.5 tonnes released to air. The release value for this example is 0.068 tonnes. If the sum of all PM10 releases at the facility is less than 0.5 tonnes, a substance report is not required for PM10.

References

US Environmental Protection Agency (US EPA), 1998. "Section 313 of the Emergency planning and community right-to-know act - EPCRA section 313 questions and answers," Office of Pollution Prevention and Toxics, revised 1998 version, EPA 745-B-98-004, December 1998.

US Environmental Protection Agency (US EPA), 1994. "Development of particulate and hazardous emission factors for electric arc welding," revised final report, EPA contract no. 68-D2-0159, MRI project no. 4601-02, May 20, 1994

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