Welding activities: guide to reporting

Purpose

To provide guidance to facilities with welding activities on how to report to the National Pollutant Release Inventory (NPRI).

Background Information

NPRI substances associated with welding activities occurring at a facility need to be considered when performing the threshold calculations. In order to correctly perform threshold calculations for welding activities you will need to understand the terms "article" and "due care".

An "article" is defined as a manufactured item that does not release an NPRI substance, when it undergoes processing or 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. Exercising "due care" in ensuring 100% recycling means that the facility generated less than 1 kg of the NPRI Part 1A substance as waste during the calendar year. Due to the significantly lower thresholds associated with Part 1B substances, there is no due care criteria for Part 1B substances and all manufacture, process or otherwise use (MPO) must be included in the threshold calculation for each substance.

The primary NPRI substances of concern used in the welding process are the Part 1A and 1B metals. However, Part 4 substances - Criteria Air Contaminants (CAC) are also released during the process. The main CAC's of concern are total particulate matter (TPM), particulate matter less than or equal to 10 microns in diameter (PM10), particulate matter less than or equal to 2.5 microns in diameter (PM2.5), carbon monoxide (CO), and oxides of nitrogen (NOx).

Types of Welding in Canada

There are two main welding processes generally found in Canada:

  1. Consumable Electrode Processes - e.g., shielded metal arc welding (SMAW), flux cored arc welding (FCAW), gas-metal arc welding (GMAW), and submerged arc welding (SAW). SMAW is the most common welding process. Welding rods and wire are similar and are considered consumable electrodes.
  2. Non-Consumable Electrode Processes - e.g. gas-tungsten arc welding (GTAW), plasma arc welding (PAW), and fusion welding.

Note: Soldering activities are not considered to be a welding operation, although NPRI reporting still applies to soldering activities.

Consumable Welding Electrode Processes

Parts 1 A&B Metals

The following points can be used to determine which sources of NPRI substances need to be considered in the threshold calculations:

  • The weight of the NPRI-listed substances found in the consumable welding electrodes must be calculated. The Material Safety Data Sheet (MSDS) can be used to determine the composition of the welding electrode. This combined with the mass of the specific electrode used can determine the amount of the NPRI substances manufactured, processed or otherwise used (MPO).
  • For Part 1A metals (ex. Cr3+, Co, Mn and Ni, or any other) facilities need to determine if they MPO greater than or equal to 10 tonnes of each substance based on the amount and composition of the consumable welding electrodes. If these substances are MPO in other processes at the facility, these sources must also be considered in your facility's threshold calculations.
  • For Part 1B metals (ex. hexavalent chromium (Cr6+), and lead, or any other) facilities will need to determine if they MPO greater than or equal to the mass threshold of each substance based on the amount and composition of the consumable materials. The mass threshold can be found in the Guide for Reporting to the National Pollutant Release Inventory. If these substances are MPO in other processes at the facility, these sources must also be considered in the facility's threshold calculations.
  • The base metal being welded retains article status and all NPRI listed substances found in it need not be considered in the threshold calculation.

After the threshold calculations have been completed and the total amounts MPO are compared to the reporting threshold, the released, recycled and disposed values must be calculated for those substances that met or exceeded the reporting threshold.

The Electric Arc Welding Spreadsheet available on the NPRI Toolbox website considers four different types of consumable electrode welding processes and various welding electrode or rod/wire types. The table below lists the types of welding rods/wire included in the spreadsheet calculations. The spreadsheet is the most preferred method of calculation.

Welding Processes and Electrode Types included in the Electric Arc Welding Spreadsheet
Welding Process - SMAW(SCC 309051xx)
Electrode Type Last 2 Digits of SCC
14Mn-4Cr (-04)
E11018 (includes E11018-M) (-08)
E308 (includes E308-16 and E308L-15) (-12)
E310 (includes E310-16) (-16)
E316 (includes E316-15, E316-16, and E316L-16) (-20)
E410 (includes E410-16) (-24)
E6010 (-28)
E6011 (-32)
E6012 (-36)
E6013 (-40)
E7018 (-44)
E7024 (-48)
E7028 (-52)
E8018 (includes E8018C3) (-56)
E9015 (includes E9015B3) (-60)
E9018 (includes E9018B3 and E9018G) (-64)
ECoCr (includes ECoCr-A) (-68)
ENi-Cl (-72)
ENiCrMo (includes ENiCrMo-4) (-76)
ENi-Cu (includes ENi-Cu-2) (-80)
Welding Process - GMAW(SCC 309052xx)
Electrode Type Last 2 Digits of SCC
E308L (ncludes E308LSi) (-12)
E70S (includes E70S-3, E70S-5, and E70S-6) (-54)
ER1260 (-10)
ER5154 (-26)
ER316 (includes ER316I-Si and ER316L-Si) (-20)
ERNiCrMo (includes ENiCrMo-3 and ENi-CrMo-4) (-76)
ERNiCu (includes ERNiCu-7) (-80)
Welding Process - FCAW(SCC 309053xx)
Electrode Type Last 2 Digits of SCC
E110 (includes E110TS-K3) (-06)
E11018 (-08)
E308LT (includes E308LT-3) (-12)
E316LT (includes E316LT-3) (-20)
E70T (includes E70T-1, E70T-2, E70T-4, E70T-5, E70T-7, and E70T-G) (-54)
E71T (includes E71T-1 and E71T-11) (-55)
Welding Process - SAW(SCC 309054xx)
Electrode Type Last 2 Digits of SCC
EM12K (includes EM12K1 and F72-EM12K2) (-10)

If the specific consumable welding electrode process and standard welding rods/wire used is not available in the spreadsheet, and no other site specific estimation method is available for your facility activities, please contact the NPRI HelpDesk for direction.

Example:

  • Process: SMAW
  • Amount of Base Metal Welded: 14 000 tonnes during the reporting year
  • Amount of Welding Wire Used: 1 000 tonnes of E310-15 welding wire during the reporting year. The wire contains 1.3% manganese by weight, obtained from the MSDS.

(1) Determine the amount of manganese (a Part 1A substance) manufactured, processed, or otherwise used 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.

(2) Determine the amount of PM10 released from the welding process.

Remember: When using a consumable welding electrode process the base metal being welded retains its article status and therefore does not need to be considered in the threshold or release calculations.

NOTE: The Electric Arc Welding Spreadsheet available on the NPRI Toolbox website will estimate the Part 1 & 4 emissions for various types of consumable electrode welding processes, as shown in the table above.

Manganese Threshold 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, the facility must submit a manganese substance report. In this example, it is assumed that no manganese is recycled or disposed, but some manganese is released as a result of the welding activity and must be calculated.

Manganese Release Estimate

The Electric Arc Welding Spreadsheet will automatically calculate the releases for all relevant substances once the rod usage amount has been entered - for illustrative purposes, a simple calculation is show below.

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]
= 1000 [tonnes] welding rod used x 1000 [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, 2.2 tonnes of manganese would be reported 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, the facility must now report for all manganese that were released, recycled or disposed.

PM10 Threshold/ Release Calculations:

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

As mentioned above, the Electric Arc Welding Spreadsheet will automatically calculate the releases for all applicable substance once the rod usage amount has been entered - for illustrative purposes, a sample calculation is shown below.

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 1000 [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 here is 15.1 tonnes, a substance report will be required for PM10. However, all other PM10 releases at the facility must be added to the 15.1 tonnes and the resultant value reported to the NPRI.

Non-consumable Welding Electrode Processes:

A review of the welding activities guidance was undertaken in 2013 and resulted in changes to the non-consumable electrode welding direction. Minimal information was available for non-consumable electrode welding process, and as a result, this section was removed. That said, estimates will still be required if reporters have information that allows estimates to be created (provided that the applicable substance threshold has been satisfied.) Questions regarding this topic may be directed to the NPRI HelpDesk.

Other Tools and Sources of Information for Welding

The NPRI Toolbox contains a spreadsheet for calculating Part 1A, 1B and CAC releases from various consumable electrode welding processes. Note that the threshold calculations will still need to be calculated as shown above for the Part 1substances, and then the spreadsheet can be used to determine the releases of those substances.

The US EPA's WebFIRE database and AP-42 documents (section 12.19) can be used for more background information on the releases from welding processes.

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, 1004.

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