4.1 Causes of Protrusion Hazards

Causes of protrusion hazards

Domain 1H of the National Recreation and Park Association (NRPA) Certified Playground Safety Inspector (CPSI) blueprint tests whether you can name why a piece of hardware becomes an impact hazard, not merely whether you can wave a gauge. The U.S. Consumer Product Safety Commission (CPSC) Public Playground Safety Handbook, Publication 325 (July 2025), and ASTM International F1487-21 Standard Consumer Safety Performance Specification for Playground Equipment for Public Use give the vocabulary. Domain 1I will teach the gauges. This section stays on the cause: what a projection is, when it becomes a protrusion, what field conditions create that geometry, and why the same bolt is a different finding on a moving hanger than on a stationary panel.

Projection is not yet a protrusion

CPSC 2025 §1.8 defines a projection as anything that extends outward from a surface of the playground equipment and must be tested to determine whether it is a protrusion, an entanglement hazard, or both. The same section defines a protrusion as a projection which, when tested, is found to be a hazard having the potential to cause bodily injury to a user who impacts it. CPSC §3.2.2 restates the injury in inspector language: a projection is a hazardous protrusion when it can cause bodily injury to a user who impacts it, and that injury can include impalement or laceration.

Keep the words separate on the exam and in the report.

One bolt can fail the impact (protrusion) gauges and catch a drawstring. Those are two findings, two citations, and often two priorities. A clothing-catch on a slide or swinging member is typically Priority 1 entanglement (Domain 1E/1F). A protrusion that can lacerate or impale but has not been shown to catch clothing is typically Priority 2 serious. Do not collapse them into “bad hardware.”

CPSC §3.2 opens the family with a design rule, not a tape measure: projections on playground equipment should not be able to entangle children’s clothing nor should they be large enough to impale. To avoid that pair of risks, §3.2 and §3.2.2 send you to Figures 2 and 3 and to Appendix B:

• The diameter of a projection should not increase in the direction away from the surrounding surface toward the exposed end (Figure 2). A mushroomed cap, a stacked washer that widens outboard, or a decorative knob that gets bigger as it leaves the panel can hold a loop that a straight-sided stud might release, and it can present a blunter, more injurious impact face.
• Bolts should not expose more than two threads beyond the end of the nut (Figure 3). Extra threads are a ready-made spike and a clothing-catch. Recess the bolt, use a shorter fastener, or cap it so the tested geometry passes.
• Swings and slides have extra projection rules in §5.3. Those extra rules exist because motion plus impact, and motion plus incline, raise both the energy of an impalement and the likelihood of a clothing-catch.

A projection that meets Figures 2 and 3 and does not extend beyond the face of any projection gauge is still a projection. It is not a hazardous protrusion. Missing a decorative cap that does not fail a gauge is a Priority 3 maintenance item, not a Domain 1H fail.

Typical field causes you must be able to name

Memorize the cause list. Each item is a geometry that creates a projection, a citation, and a foreseeable impact or catch.

• Bolts that extend beyond the nut or recess. The classic installer error: a 3/8-inch carriage bolt left long because the next-shorter stock was not on the truck. Extra threads beyond the nut violate Figure 3. If the unthreaded shank or the threaded end stands proud enough to fail a gauge, it is a protrusion. If a drawstring or hood can cinch on it in a motion path, it is also entanglement.
• Uncapped pipe ends. CPSC §3.4 separately requires exposed open ends of tubing that do not rest on the ground to be covered by caps or plugs that cannot be removed without tools. An open pipe is a laceration rim; a broken or missing cap often leaves a circular spike that fails as a protrusion.
• S-hooks that also catch drawstrings. An S-hook or C-hook is closed only if there is no gap greater than 0.04 in (about a dime). Domain 1F already ranked an open hook on a swing as entanglement. The same hook’s wire end, if it stands proud of the seat or hanger in the impact region, is also a protrusion. Write both.
• Hardware on swing seats and hangers. CPSC §5.3.8.5 is explicit: protrusions on swings are extremely hazardous because of the potential for impact, and nothing, including bolts or other parts, on the front, back, or underside of a swing should stick out more than 1/8 in (0.12 in). Seat-end fasteners, hanger bolts, and underside cleats are the usual stations.
• Slide-bedway fasteners. CPSC §5.3.6.7 records that children have died when clothing tangled on protrusions or gaps on slides. Projections up to 3 in in diameter should not stick up more than 1/8 in from the slide, and there should be no gaps at the platform-to-chute joint. Rivets, joint offsets, and cracked plastic ridges in the travel path are high-likelihood causes.
• Exposed axle ends on rotating equipment. Merry-go-rounds, spinners, and some spring rockers hide an axle or fastener at the hub. A child circulating in the use zone, or a child who falls toward the hub, meets a rotating or fixed spike. Test the at-rest geometry and the accessible end through the motion cycle.
• Broken plastic that leaves a spike. Impact, ultraviolet aging, and vandalism snap a panel, a seat, or a slide sidewall into a dagger. The remaining shard is a projection. Gauge it. If it can impale or lacerate, it is a protrusion even though no installer put a bolt there.

CPSC Table 3 (routine inspection) lists loose bolts, missing end caps, and cracks in plastics as standing inspection items. Those maintenance notes are the precursors of Domain 1H protrusions. A missing cap that still sits flush and passes every gauge is not yet a protrusion. A missing cap that leaves a pipe rim or a bolt end is.

Worked scenario: the same 3/8-inch bolt in two places

You find a 3/8-inch (0.375 in) bolt standing 1/2 inch (0.50 in) proud of the nut in two locations on the same visit: on a to-fro swing hanger, and on a 4-foot (48 in) stationary panel of the adjacent composite.

Treat them as two different findings.

On the swing hanger. The fastener is a projection on a suspended member. CPSC Appendix B.2.2 exists because impact energy on a swinging component is not the same as a child walking into a post. Hold the special swing/slide gauge vertically with the hole axis parallel to the path of travel and fail any bolt in the potential impact region that extends through the hole beyond the face. Independently, §5.3.8.5 fails anything on the front, back, or underside of a swing that sticks out more than 1/8 in — and 1/2 in is four times that limit. The 3/8-inch shank is also thinner than the small projection gauge’s 0.50 in inside diameter and taller than that gauge’s 0.25 in height, so it fails the general B.2.1 small gauge as well. Because a hood or drawstring can cinch on the proud threads as the occupant moves, the same bolt is an entanglement catch-point. Cite §3.2, §3.2.2, §5.3.8.5, and Appendix B.2.2. Rank the clothing-catch as Priority 1; the impact protrusion would be Priority 2 if it stood alone.

On the 4-foot stationary panel. The same geometry is still a projection and still fails the general three-gauge test in Appendix B.2.1 (the small gauge hangs / the 1/2-inch proud length extends beyond the 0.25 in face). It is not automatically subject to B.2.2 or the 1/8 in swing-seat rule. The foreseeable path is a child running into the panel or falling against it, not a moving member striking the child. Unless the bolt sits in a slide path or another clothing-cinch path, write a protrusion finding, not a Priority 1 entanglement. Cite §3.2.2, Figures 2 and 3 (more than two threads), and Appendix B.2.1. Rank it Priority 2 serious and give a short correction deadline.

Do not tell the owner “it’s the same bolt, so it’s the same hazard.” Location, motion, and the extra §5.3 rules change both the test and the likelihood.

How causes become ranked findings

Name the hardware (proud bolt, uncapped pipe, broken plastic spike, exposed axle), name the injury pathway (impalement, laceration, and, if present, clothing-catch), cite CPSC §3.2 / §3.2.2 / Figures 2 and 3 / the matching §5.3 swing or slide rule, then rank. Domain 1I will confirm the fail with a named gauge. Domain 1H is already failed when you can explain why that geometry can impale, lacerate, or catch clothing.

Exam-ready checklist

• Projection = extends and must be tested. Protrusion = tested impact hazard.
• The same fastener can be a protrusion and an entanglement catch-point.
• Figures 2 and 3: no increasing diameter toward the exposed end; no more than two threads beyond the nut.
• Swings and slides add 1/8 in and path-specific rules; do not apply only the general gauges there.
• A 3/8-inch × 1/2-inch proud bolt on a hanger is not the same finding as the same bolt on a 4-foot stationary panel.