One of the most frustrating experiences for IBC tote owners is discovering that their new adapter, hose, or fitting doesn't thread onto their valve. The reason: IBC totes manufactured in different countries use different thread standards, and even within a single standard, multiple sizes exist. This guide demystifies IBC threading once and for all.
The Four Main Thread Types on IBC Totes
### 1. NPS (National Pipe Straight) — Also Called NPS or NPSM
Origin: United States Where you'll find it: IBCs manufactured in North America or destined for the US market Common sizes on IBCs: 2" NPS (most common for bottom valves), 6" NPS (fill caps)
Characteristics: - Straight (parallel) threads — not tapered - 11.5 threads per inch for 2" size - Measured by nominal pipe size (the actual outer diameter of a 2" NPS thread is approximately 2.375 inches) - Seals with a gasket, not thread interference
Important note: NPS (straight) is different from NPT (tapered). IBC valves use NPS/NPSM straight threads because they need to be assembled and disassembled repeatedly. NPT tapered threads are designed for permanent pipe connections.
### 2. BSP (British Standard Pipe) — Also Called BSPP or G-Thread
Origin: United Kingdom, used throughout Europe, Asia, Australia Where you'll find it: IBCs manufactured in Europe or Asia (Schütz, Mauser European production) Common sizes on IBCs: 2" BSP (DN50) for bottom valves, 6" BSP (DN150) for fill caps
Characteristics: - Straight (parallel) threads — similar concept to NPS but different dimensions - 11 threads per inch for 2" size - Measured differently than NPS (2" BSP has an actual OD of approximately 2.347 inches) - Seals with a gasket (bonded washer seal)
### 3. Buttress Thread (S-Type or S60x6)
Origin: European DIN standard Where you'll find it: Very common on European-made IBCs, increasingly found worldwide Common size on IBCs: S60x6 (60mm diameter, 6mm pitch) for bottom valve outlets
Characteristics: - Large, coarse threads designed for quick hand-tightening - Asymmetric thread profile (strong in one direction, easy to engage from the other) - Only 2-3 full turns to engage fully - Seals with an O-ring or flat gasket
Why it's popular: Buttress threads allow quick, tool-free connection and disconnection — ideal for hose adapters, camlock fittings, and dispensing accessories that are frequently changed.
### 4. Tri-Sure / Rieke Thread (Fine Thread Caps)
Origin: Proprietary standards from closure manufacturers Where you'll find it: On 2" bung openings (top fill ports on some IBCs) and some older valve configurations Common size: 2" fine thread, approximately 56mm
Characteristics: - Fine threads designed for chemical-tight seal - Requires specific wrenches for removal - Less common on modern IBCs but still found on older inventory
Identifying Your Thread Type
If you don't know what thread your IBC has, use these identification methods:
Visual inspection: - Count threads per inch using a thread pitch gauge or ruler - NPS 2" = 11.5 TPI - BSP 2" = 11 TPI - Buttress S60x6 = very coarse, about 4.2 TPI equivalent
Measure the outer diameter: - NPS 2" = 2.375" (60.3mm) OD - BSP 2" = 2.347" (59.6mm) OD - Buttress S60x6 = 60mm OD
Try a known fitting: If you have access to fittings of known thread types, the simplest test is to try threading them on. A fitting should engage smoothly without forcing — cross-threading damages both components.
Check the manufacturer: If you know the IBC brand and origin country: - Schütz (Germany): Typically buttress S60x6 on valve outlet, BSP or buttress on fill cap - Mauser (Germany/global): Varies by production facility — European plants use buttress, US plants often use NPS - Greif (US): Typically NPS - Snyder (US): NPS - Hoover (US): NPS
Common Adapter Combinations
Because thread standards vary, the adapter market is robust:
- **NPS to garden hose:** 2" NPS female x 3/4" GHT male
- **BSP to NPS:** 2" BSP male x 2" NPS female (straight conversion)
- **Buttress S60x6 to NPS:** S60x6 female x 2" NPS male
- **Buttress S60x6 to garden hose:** S60x6 female x 3/4" GHT male
- **Any thread to camlock:** Various adapters available for quick-connect conversion
- **Buttress S60x6 to BSP:** S60x6 female x 2" BSP male
Gaskets and Sealing
All IBC threaded connections (regardless of type) rely on gaskets for seal: - Standard EPDM gaskets for water and mild chemicals - Viton gaskets for aggressive chemicals and solvents - PTFE gaskets for food-grade and pharmaceutical applications - Silicone gaskets for high-temperature applications
When changing adapters, always inspect and replace the gasket if worn, compressed, or chemically attacked.
Pro Tips
1. Never force a fitting. If it doesn't thread smoothly by hand for the first few turns, you likely have a thread mismatch. 2. Don't use Teflon tape on straight threads. NPS and BSP straight threads seal with gaskets, not tape. Tape is for NPT tapered threads only. 3. Buy adapters from IBC specialty suppliers rather than general hardware stores — they understand the specific standards involved. 4. Keep a thread identification kit if you regularly work with IBCs from multiple sources. 5. When ordering replacement valves, specify both the inlet thread (connects to IBC bottle) and outlet thread (where your hose/adapter connects) — they may be different standards.