Identifying an IBC thread from a photograph

The nominal size of an outlet — two inch, three inch — describes the bore, not the thread. Two containers with two-inch outlets can have completely different threads, and an adapter for one will not start on the other.

The three standards you will meet

Camlock and tri-clamp are not native threads — they are adapters fitted onto one of the above. If your container already has a camlock on it, somebody has already made this decision and you need to know what is underneath.

How to take a photograph that answers the question

1. 01Remove the outlet cap first. The thread on the outlet, not the cap, is what matters.
2. 02Take one shot square on to the opening, filling the frame.
3. 03Take a second at about thirty degrees so the thread profile is visible in silhouette.
4. 04Put a tape measure or a ruler across the opening in one of the shots, laid on the thread crests.
5. 05Include any moulded or stamped markings near the outlet, which sometimes name the standard outright.

What we actually check

Outside diameter across the crests, pitch counted over a known length, thread profile, and whether the thread is single or multi-start. Then the container itself — manufacturer, age and format all narrow the possibilities quickly, because the standards cluster by design family.

About one in twenty photographs is ambiguous, usually because the thread is damaged or the picture is straight-on only. In those cases we ask for the second angle and it resolves.

Adapters, briefly

• Buttress to camlock — the workhorse. Type A through F describe male or female and thread or hose end.
• Buttress to garden hose thread — 3/4 inch GHT, for rain systems and irrigation.
• Buttress to NPT — for pipe connections.
• Buttress to tri-clamp — sanitary service, food and beverage lines.
• Reducers between S100x8 and S60x6, for mixed fleets.

Whichever you fit, match the gasket to the fluid rather than to whatever came in the bag. That is the other half of the decision and it is the half that fails.

One thing not to do

Do not force a fitting that will not start cleanly. Buttress threads are coarse and forgiving enough that a wrong adapter can be persuaded partway on, and the result is a damaged outlet on a container that was fine.

Measuring without a thread gauge

You do not need specialist tools. A tape measure and a phone answer the question ninety-five percent of the time.

1. 01Lay a tape across the opening on the thread crests, at the widest point. That is the outside diameter.
2. 02Mark a start point on one thread crest, count ten full turns along the thread, and measure the distance. Divide by ten for the pitch.
3. 03Look at the thread in profile against the light. Sawtooth is buttress; symmetrical triangle is a V thread.
4. 04Note whether it is a single thread or several starting at different points around the circumference.

Sixty millimetres across with a six millimetre pitch and a buttress profile is S60x6, which is the majority answer. A hundred millimetres with an eight millimetre pitch is S100x8.

Adapter chains, and why to avoid them

It is possible to stack adapters — buttress to NPT, NPT to camlock, camlock to hose. Each junction is a potential leak, a restriction and something to lose.

A single adapter that goes straight from the container thread to your connection is nearly always available and is always the better answer. If you find yourself buying three fittings, ask whether one exists.

Material choice for adapters

The most frequent mismatch we see is an aluminium camlock on a salt brine line, which corrodes steadily and eventually seizes. Stainless costs more once.

Threads on stainless vessels

Stainless IBCs generally do not use buttress threads at all. Expect tri-clamp ferrules, NPT or BSP threads and bolted manways, and expect the sizes to follow sanitary or pipe standards rather than container ones.

If you are moving from composite to stainless, assume none of your existing adapters transfer.

Questions about fittings

Can I reuse the adapter from an old container? Usually, if the thread matches and the gasket is replaced. Adapters are durable; their seals are not.

What is a camlock type letter? It describes the configuration: A is a male adapter with a female thread, B is a female coupler with a male thread, C is a female coupler with a hose shank, D is a female coupler with a female thread, E is a male adapter with a hose shank, F is a male adapter with a male thread. Getting the letter wrong is the most common ordering error.

Do I need a valve as well as an adapter? The container has a valve. The adapter goes on the outlet in front of it. If your container has no valve, that is a separate part and we sell those too.

Can you fit the adapter before shipping? Yes, and we would rather. Tell us the connection and the fluid at quote time and the container arrives ready to use.