Short answer: Most oilfield, electrical, and industrial workers in Oklahoma and Texas need CAT 2 flame-resistant (FR) clothing — gear with an arc rating of at least 8 cal/cm². Higher-energy work calls for CAT 4 (40 cal/cm²). Your employer's arc-flash hazard assessment sets the exact requirement for your job site — but if no one has given you a number, CAT 2 is the practical baseline for day-to-day oilfield FR.
FR ratings confuse a lot of people, and the labels don't help. Here's the plain-English version from a store that's been fitting Oklahoma and Texas work crews since 1980.
FR vs. arc-rated: two different hazards
There are two separate risks FR clothing protects against, and two standards behind them:
- Flash fire — a brief, intense fire, such as a gas ignition on a rig. Garments tested against this carry an NFPA 2112 certification.
- Arc flash — an electrical explosion from a fault in energized equipment. Protection here is governed by NFPA 70E, and garments are given an arc rating measured in calories per square centimeter (cal/cm²).
Most oilfield FR clothing we carry is dual-hazard — certified to NFPA 2112 and arc-rated — so you're covered for both.
What do CAT 1, 2, 3 and 4 mean?
"CAT" (PPE Category, formerly HRC — Hazard Risk Category) is NFPA 70E's way of grouping arc-flash protection levels. Each level has a minimum arc rating:
- CAT 1 — minimum 4 cal/cm². Often used as an FR base layer. On many oilfield and industrial sites, CAT 1 by itself isn't enough for your primary outer layer, but it's commonly worn underneath CAT 2 or CAT 4 gear to increase protection and improve comfort.
- CAT 2 — minimum 8 cal/cm². The most common requirement for oilfield, utility, and general industrial work.
- CAT 3 — minimum 25 cal/cm².
- CAT 4 — minimum 40 cal/cm². Typically reserved for higher-energy electrical work and specific high arc-flash-hazard tasks.
The number on a garment tag — its ATPV (Arc Thermal Performance Value) — is the actual tested arc rating. A shirt with an ATPV of 8.7 cal/cm² qualifies as CAT 2.
How do I know which CAT level I need?
This isn't a guess. OSHA requires your employer to perform an arc-flash hazard assessment for the tasks and equipment you work around. That assessment produces the required minimum arc rating — and that's the number your FR clothing has to meet or beat.
If you're a contractor or new hire and nobody has handed you a spec, ask your safety manager. In our experience outfitting Oklahoma and West Texas oilfield crews, CAT 2 covers the large majority of day-to-day rig and field work, with CAT 4 reserved for higher-energy electrical tasks.
Why an FR base layer matters
This is something we explain to crews all the time. Many workers throw a regular cotton T-shirt under their FR gear without thinking about it. The problem is sweat and heat: in a flash-fire or arc-flash event, moisture trapped in clothing can rapidly turn to steam and contribute to burns.
That's one reason many oilfield and industrial workers wear a CAT 1 FR base layer under their CAT 2 or CAT 4 gear. It adds arc protection, keeps non-FR materials off your skin, and can increase your total protective system rating through layering — arc ratings stack when you layer FR over FR.
Important: a base layer doesn't replace your required outer-layer CAT rating. If your site requires CAT 2, you still need CAT 2 as your primary protection — the FR base layer is added protection on top of that, not a substitute.
Frequently asked questions
Is CAT 2 enough for oilfield work?
For most general oilfield and field tasks, yes — but your employer's hazard assessment has the final word. Never go below the rating your job specifies.
What should I wear under FR clothing?
An FR base layer is the safe choice — ideally a CAT 1 FR shirt. A regular cotton tee isn't flame-resistant and traps sweat; synthetic athletic shirts (polyester, nylon) are worse, because they can melt in a thermal event. When in doubt, keep FR against your skin.
What's the difference between flash fire and arc flash protection?
Flash fire (NFPA 2112) is about brief fuel fires; arc flash (NFPA 70E, arc rating) is about electrical faults. Most quality oilfield FR is certified for both.
Does FR clothing wear out?
The flame resistance in quality FR fabric — Bulwark EXCEL FR, Carhartt FR, Wrangler FR, Ariat FR — is built into the fiber and lasts the life of the garment. But worn, torn, or heavily contaminated garments lose protection, so replace them.
Can I wash FR clothing at home?
Yes, but skip bleach, fabric softener, and starch — they can coat the fabric or leave flammable residue. Follow the garment's care tag.
Still not sure what you need? Bring your job spec into our Elk City store or give us a call — we fit FR gear for Oklahoma and Texas oilfield and industrial workers every week, and we'll match you to the right CAT level. Browse men's FR clothing to see what we carry.