NIBCO - I05555H U5807 3 HXH 90 ELBOW ABS, Black, 3"

What it is and where it shines

I’ve leaned on a lot of ABS-DWV fittings over the years, and this 3-inch ABS 90° elbow from NIBCO has become one of my go-to parts when I need a dependable quarter-bend with hub ends. It’s a straightforward fitting: hub x hub, designed to join two unthreaded pipes or fittings at a clean right angle in drain, waste, and vent systems. The black ABS material is exactly what I expect—lightweight, tough enough for jobsite bumps, and consistent in wall thickness and socket depth.

If you work on residential DWV or do any RV plumbing repair, you’ll recognize why this piece matters. The 3-inch size is common for main soil lines and black-tank drain runs, and a good 90 can save time and frustration when routing around framing or tank geometry. The NIBCO elbow hits the key marks: true angle, smooth interior, and reliable solvent-weld sockets.

Build, material, and standards

The elbow is injection-molded ABS-DWV, not a pressure-rated product—and that’s exactly what you want in a drain fitting. ABS resists many common household chemicals, holds up in a wide temperature range, and weighs very little compared with cast metal or even some PVC fittings. The interior surface is slick and uniform, which reduces turbulence and the chance of buildup at the bend—more important than it sounds on horizontal runs or in RV black-tank plumbing.

The marking on the body indicates conformance with ASTM D2661 and D3311. That’s not just alphabet soup; it means dimensions are standardized, sockets are sized correctly for 3-inch DWV pipe, and the elbow geometry is consistent. In practice, that translates into a reliable fit with pipe from different manufacturers and predictable solvent-weld results.

Fit and finish

On the bench, the hubs were round, cleanly molded, and free of flash. My test pipe seated to a consistent depth in both ends, and the interference fit felt right—not overly tight, not sloppy. The 90° angle checked square against a machinist’s square. Internally, the bend is smooth with no ridges. That smoothness pays off over time, especially in low-slope drains or RV systems where solids need all the help they can get to move along.

The exterior carries legible markings—size, material, and standard—which is nice for inspections and helpful when you’re rummaging through a bin of black fittings and need to confirm size at a glance.

Installation experience

ABS is about as user-friendly as it gets for DWV. I installed this elbow on a 3-inch ABS line, using a one-step ABS cement. No primer is required for ABS in most jurisdictions (always check your local code). Here’s the workflow that’s served me well:

• Dry-fit the assembly and confirm alignment.
• Mark the pipe and fitting for orientation.
• Wipe off dust and moisture.
• Apply even cement to the pipe and the hub.
• Insert fully and give a quarter-turn to distribute cement.
• Hold for a few seconds to prevent push-out, then support while it sets.

The elbow provided a snug, even bond, and the squeeze-out bead was uniform around the circumference. Cure time was typical for ABS; handling strength within minutes, full cure per the cement manufacturer’s schedule. Because ABS is lighter than PVC, securing the assembly overhead was easy—less fighting gravity while the joint sets.

In an RV repair, the same process applied, with two added considerations: supporting the pipe to account for vehicle vibration and allowing adequate slope to the gate valve. The elbow’s hubs took standard RV ABS pipe with no surprises.

Performance and use cases

Installed vertically (vent stack transitions) or moving from vertical to horizontal, the elbow performs as expected—zero drama. On horizontal-to-horizontal connections, I’m more selective. This is a standard 90 (often called a quarter bend), not a long-sweep elbow. For many codes and best practices, long sweeps are preferred for horizontal directional changes to reduce the risk of clogging and to maintain better flow characteristics. That’s not a knock on this fitting; it’s about using the right geometry for the right situation. When used appropriately, this elbow provides a tight, space-saving turn that’s strong and consistent.

Where it excels:
- Tight framing bays where a long sweep simply won’t fit.
- Vertical-to-horizontal transitions where code permits a quarter bend.
- RV drain repairs, especially around tanks and termination assemblies.
- Compact appliance or fixture vents where space is at a premium.

Limitations and code considerations

A few important caveats, most of which apply to any ABS 90:

• DWV only: This is not for pressurized systems or potable water.
• Short-turn geometry: For horizontal-to-horizontal runs, many jurisdictions require a long sweep. Always verify with local code.
• Material transitions: Don’t solvent-weld ABS to PVC unless a local code explicitly allows a listed transition cement (many do not). Generally, use a shielded no-hub coupling to join ABS to PVC.
• UV exposure: ABS can degrade with prolonged direct sunlight. In exterior or exposed RV applications, shield the fitting.
• Temperature extremes: ABS handles cold better than PVC but can still become brittle in very low temperatures. Handle carefully in winter.

None of these are flaws in the elbow; they’re just the realities of ABS-DWV and good plumbing practice.

Comparisons and context

Compared with PVC:
- Ease of bonding: ABS is typically a one-step cement process; PVC usually needs primer plus cement.
- Cold-weather behavior: ABS tends to be more forgiving when temperatures drop, which is valuable for outdoor or RV work.
- Noise and rigidity: PVC can be a hair quieter in some in-wall stacks; ABS is lighter and often faster to work with.

Compared with long-sweep elbows:
- Space: This 90 saves space where a long sweep won’t fit.
- Flow: Long sweeps are gentler on flow in horizontal runs. I choose the geometry based on the direction change and code.

As for brand consistency, NIBCO’s molding has been reliable in my experience. Socket tolerances have been predictable, and I haven’t run into out-of-square or warped pieces—a small thing that becomes a big headache when it’s wrong.

Tips for a clean install

• Dry-fit everything and mark orientation lines across the hub and pipe. This prevents “surprise” misalignment once the cement grabs.
• Be mindful of slope: For 3-inch horizontal drains, 1/4 inch per foot is a common target (check code).
• Deburr cuts. A quick touch with a deburring tool or utility knife keeps shavings out of the joint and improves flow.
• Support the assembly. Use proper hangers so the joint isn’t bearing the weight of a long run.
• In RVs, plan for movement. Add support near the elbow to reduce stress from vibration and thermal expansion.

Durability and maintenance

Once solvent-welded, the joint is structural. I’ve seen ABS elbows like this hold up for years behind walls and underneath rigs, provided they were installed correctly and protected from impact and UV. Maintenance is more about the system than the fitting: use appropriate cleanouts, avoid harsh chemicals that aren’t rated for ABS, and keep an eye on hangers and supports.

Who it’s for

• DIYers updating a bathroom or replacing a section of DWV where a 3-inch turn is required.
• RV owners repairing or reconfiguring black-tank drain assemblies.
• Pros who need a reliable, standardized elbow that plays nicely with common 3-inch ABS pipe and fittings.

Final recommendation

I recommend this NIBCO 3-inch ABS 90° elbow for DWV and RV applications where a standard quarter-bend is appropriate. It’s dimensionally accurate, easy to bond, and built to recognized standards, with a smooth interior that encourages good flow. Use it within its lane—DWV only, and favor long sweeps where code or best practice calls for them—and it will do exactly what you need without fuss. If you’re repairing an RV black-tank drain or making a compact turn in a residential waste line, this elbow is a dependable, no-surprises choice.