KTA’s Certified Coating Inspector Forum Volume 2, Issue No. 5 – May 2023
William Corbett, COO
AMPP Senior Certified Coating Inspector & Certified Protective Coating Specialist
KTA’s Certified Coating Inspector Forum is designed to provide professional development/continuing education on standards, inspection practices, new instruments, and other topics to help keep certified AMPP and FROSIO coating inspectors current. It represents the views of the author and KTA-Tator, Inc. It may or may not represent the views of AMPP: The Association for Materials Protection & Performance, even though SSPC, NACE, and AMPP standards are frequently referenced in the content.
Containments are frequently erected prior to surface preparation and coating application operations to contain debris and overspray. That is, containments help to protect the environment and public health and welfare. These same containments are ventilated (cross draft or down draft) using air make-up ports and exhausts equipped with dust collectors to protect workers inside the containment and control emissions. Coating inspectors enter containments after surface preparation and after coating application to perform inspections of the work. This article introduces the subject of containments and their components, describes methods of verifying containment and ventilation effectiveness, and describes the inspector’s role for ensuring performance of the containment on a coating project when required in their scope of responsibilities.
SSPC Guide 6, Guide for Containing Surface Preparation Debris Generated During Paint Removal Operations was first published as an interim guide in March 1993, two months before OSHA formally released their interim final rule on lead in construction. During the same time, the painting industry was seeking clarification from the US Environmental Protection Agency (USEPA) on the applicability of existing regulations for the protection of the public and the environment during lead disturbing activities. Since the extent of the restrictions over emissions was not immediately forthcoming, the Guide described different classes of containment ranging from little control over dust and debris to extensive controls. In this way, when the extent of controls was established by regulation or specification, the Guide would already have a class of containment available that could be used to achieve compliance. Although the control of emissions has been better clarified since the early 1990’s, the different classes of containment have remained. The latest version of the Guide (as of the posting of this column) is 2021. While a Guide is not a standard, SSPC Guide 6 is widely specified on paint removal projects, independent of the type and concentration of toxic metals, if any, in the existing coating system. Containments are used to control nuisance dust and overspray, as well as contain spent abrasive, rust, mill scale and paint chips. Note that containment for paint application is not addressed by SSPC Guide 6 and is not discussed further in this article.
SSPC Guide 7, Guide to the Disposal of Lead Contaminated Surface Preparation Debris (2015) provides information regarding handling, testing, and disposal of solid debris generated during preparation of surfaces previously painted with lead-containing paint. This guide is also frequently invoked by project specifications to help ensure the debris the containment and dust collector capture is handled and disposed of according to regulations. The focus of this column will be on Guide 6.
SSPC Guide 6 includes tables addressing four different coating removal methods (dry abrasive blast cleaning [A], wet methods [W], chemical stripping [C], and power tool cleaning [P]). Each of these methods has multiple classes, with Class 1 denoting the greatest control of emissions and Class 3 or 4 denoting the lowest level of control:
A: Abrasive Blast Cleaning (Classes 1A, 2A, 3A, 4A)
W: Water Blasting or Water Jetting (Classes 1W, 2W, 3W, 4W)
C: Chemical Stripping (Classes 1C, 2C, 3C)
P: Power Tool Cleaning (Classes 1P, 2P, 3P)
A number of different containment and ventilation components for each removal method and classification are described in the Guide. For the Containment System, the components include the following, with a few options available within each Component Type (as shown in parenthesis):
Type A. Containment Materials (rigid or flexible)
Type B. Penetrability/Permeability of the Containment Materials (air impenetrable/penetrable, water impermeable/permeable) as well as chemical resistance (applicable to chemical stripping paint removal method)
Type C. Support Structure for the containment (rigid [e.g., scaffolding-shown], flexible [e.g., wire cables], or minimal)
Type D. Joints (full or partial seal [shown])
Type E. Entryway (airlock [shown], resealable, overlap, or open seam)
For the Ventilation System, the components include the following, again with a few options available within each Component Type (shown in parenthesis):
Type F. Air Make-Up (controlled or open, e.g., the size and number of air entry ports in the containment [slits or flaps] that allow fresh air to enter the containment)
Type G. Input Airflow (forced [e.g., fans/blowers] or natural)
Type H. Negative Air Pressure (instrument [manometer or magnehelic gauge] or visual verification [flexible containment materials are concave or sucked inward])
Type I. Air Movement (minimum specified or not specified). Typical industrial ventilation requirements include minimum 100 ft/min. cross draft or minimum 60 ft/min. downdraft)
Type J. Exhaust Dust Filtration (Filtration [collected dust is trapped on filters prior to air being exhausted back into the atmosphere] or no controls/not required).
As shown by each “Type” above, there are options for each of the components that the specifier may or may not require. For example, for the most rigorous containment for abrasive blast cleaning (Class 1A), the containment may be rigid (e.g., plywood) which is called Type A1, or flexible (e.g., tarps) which is called Type A2. If the specifier wants to mandate the use of rigid materials, they would specify Type A1 – Rigid. If the specification is silent, then either rigid or flexible materials can be used.
SSPC Guide 6, when abrasive blast cleaning is used, Class 1A containment and ventilation requirements are frequently invoked on projects involving total removal of a coating system containing toxic metals (e.g., lead) from a structure. Further, containment materials are often required to be fire retardant.
Methods of Verifying Containment and Ventilation Effectiveness
A containment is designed to protect the environment and the public, and the ventilation system is designed to both control emissions and protect workers inside the containment. To ensure the effectiveness of these systems it is prudent to monitor performance during coating removal operations. This can include monitoring for potential releases to the air, soil, and/or water surrounding the structure, as well as measuring air flow through the interior of the containment.
Details on methods of monitoring are found in SSPC-Technology Update No. 7, Conducting Ambient Air, Soil, and Water Sampling of Surface Preparation and Paint Disturbance Activities, briefly summarized as follows. The air immediately surrounding the project can be monitored for particulate (total suspended particulate, 10 microns and larger, or 2.5 microns and larger). Total Suspended Particulate or TSP monitoring is most common. Special filters capture all airborne particulate (independent of size) in the vicinity of the monitor for subsequent laboratory analysis for lead. Since the volume of air drawn across the filter (in cubic feet/minute) is known, the concentration of lead (in micrograms/m3) can be calculated and compared to the threshold specified.
Alternatively (or in addition), visible emissions monitoring can be performed, where dust emissions escaping the containment are timed and compared to the threshold specified, ranging from Level 0 (no emissions) to Level 4 (unrestricted emissions). Level 1 emissions are commonly specified, which are a cumulative duration of no greater than 1% of the workday, or cumulative 5 minutes of emissions in an 8-hour workday. Typically, however, when any visible emissions are observed, operations are immediately halted until the source of the emissions is fixed (e.g., a hole in the containment tarp is repaired). If emissions exceed the specified threshold (e.g., 1% of the workday), the specification may require suspension of operations for the day.
Another way to control emissions from escaping into the air is to maintain negative pressure inside the containment. While negative pressure can be visually verified by the concave appearance of flexible containment materials like tarps, this same appearance can be created by wind. Therefore, a manometer or magnehelic gauge can be used, which can also quantify the actual pressure. A magnehelic gauge contains two ports. One port contains a piece of tubing that is inserted through the containment wall; the other port is open to the environment outside of the containment. The pressure differential is read from the gauge dial; typically, a minimum of 0.03” water column (wc) is required.
Pre- and post-project soil and water sampling can be performed, but sampling fast moving bodies of water is often considered useless, and soils often contain lead so pre- and post- project samples need to be collected from the same locations and the delta calculated. Frequently, visual examination of the ground after the project is complete is done in lieu of post-project soil sampling. Again, a detailed description of all the methods of monitoring and sampling can be found in SSPC-TU7.
Monitoring Ventilation Inside Containment
Rotating Vane Anemometers (RVAs) are commonly used to verify adequate airflow inside a containment. RVAs typically read-out in miles/hour or feet/minute and can be used to measure cross draft or downdraft air velocities. These velocities are typically measured and recorded in feet/minute.
As a coating inspector, it is best to let the dust collector operate for a minimum of 15-20 minutes after surface preparation activities involving abrasive blast cleaning have stopped before entering the containment for inspection. This will enable you to see better and the airborne concentrations of particulate will be substantially lower.
Note that inspectors, like surface preparation and painting personnel, must wear proper PPE, follow hand washing procedures after leaving the containment, and are prohibited from eating, drinking, or using tobacco products inside the regulated area (an area typically demarcated with caution tape and signage where the concentration of airborne lead exceeds the OSHA Action Level of 30µg/m3).
The Inspector’s Role
An Inspector’s role related to containment erection and maintenance will vary depending on:
- Scope of responsibility on the project
- Quality Control Responsibilities (where the contractor requires the QC Inspector to also be the lead competent person/supervisor)
- Quality Assurance Responsibilities (where the owner wants assurance that the contractor is complying with specification requirements and regulations).
The QA Inspector (representing the owner) may be required to perform the containment submittal review and acceptance, verify the containment “as built” matches the containment “as designed,” and monitor surface preparation operations to verify the contractor is complying with the environmental protection requirements invoked by contract.
The QC Inspector or Competent Person (representing the contractor) is typically responsible for verifying that the containment is effective in protecting the environment and that there is adequate airflow inside the containment. They may also perform visible emissions monitoring and confirm that the specified sampling and instrument monitoring are performed and take immediate action if the containment is breached.
Note that AMPP CIP training and certification does not qualify an inspector to perform worker protection, environmental, or waste management monitoring on a project. Rather, AMPP C3 (32-hour initial training) and AMPP C5 (8-hour annual refresher training) are typically required to monitor the types of controls described in this article.
Containments are frequently erected to protect the environment and public health and welfare. These same containments are often ventilated to protect both the environment and the workers inside. Coating inspectors frequently enter the containment to perform inspections of surface preparation and coating application work. This article introduces the subject of containments and their components, describes methods of verifying containment and ventilation effectiveness, and describes the inspector’s role for ensuring performance of the containment on a coating project when required in the scope of responsibilities.