ISO 1481 Slotted Pan Head Tapping Screws
ISO 1481 slotted pan head tapping screws ST 2,2 to ST 9,5 — the classic slotted pan sheet-metal screw, with the collected full geometry ladder and the trade-size availability matrix per thread.
Last updated: 2026-11
Specifications
ISO 1481 is the oldest-looking member of the tapping family and still the most common in maintenance work: a rounded pan head over a single slot, driving with a plain flat blade. The dome spreads the clamping load over a wider footprint than a countersunk head and needs no countersink prep — drop it into a plain hole and let the thread roll. The collected table runs ST 2,2 to ST 9,5 (the largest ST size in this batch) with the full geometry set: body diameter da, head diameter dk max./min., head height k max./min., slot width n in its nominal/max./min. triple, pan radius rf, slot depth t and slot-base width w minimums, and the y Type C/F thread-end allowances. The trade-size matrix marks which length/thread combinations the standard offers — l 4,5 to 50, with "+" in the source's own notation — so availability, not geometry, is the real constraint when substituting. Slotted heads tolerate paint-fouled sockets and hand driving but cam out under power torque; that limitation is mechanical reality, not a spec. Property class, material and finish are not tabulated by the collected specification — per RFQ.
| Standard | ISO 1481 — tapping screws, slotted pan head |
|---|---|
| Size range | ST 2,2 – ST 9,5 (largest size in the collected ladder) |
| Head geometry | dk max. 4 → 20 mm; k max. 1,3 → 6; rf approx. 0,6 → 3 |
| Slot | n nominal 0,5 → 2,5; t min. 0,5 → 2,4; w min. 0,5 → 2,4 |
| Thread-end allowance | y Type C 2 → 8 / Type F 1,6 → 4,2 per size |
| Trade sizes | l 4,5 – 50 availability matrix, "+" marks the source's offered pairs |
| Material / finish | Not tabulated by the collected specification — per RFQ |
| Attribute | Limit | ST 2,2 | ST 2,9 | ST 3,5 | ST 4,2 | ST 4,8 | ST 5,5 | ST 6,3 | ST 8 | ST 9,5 |
|---|---|---|---|---|---|---|---|---|---|---|
| P | 0,8 | 1,1 | 1,3 | 1,4 | 1,6 | 1,8 | 1,8 | 2,1 | 2,1 | |
| a | max. | 0,8 | 1,1 | 1,3 | 1,4 | 1,6 | 1,8 | 1,8 | 2,1 | 2,1 |
| da | max. | 2,8 | 3,5 | 4,1 | 4,9 | 5,5 | 6,3 | 7,1 | 9,2 | 10,7 |
| dk | max. | 4 | 5,6 | 7 | 8 | 9,5 | 11 | 12 | 16 | 20 |
| dk | min. | 3,7 | 5,3 | 6,6 | 7,6 | 9,1 | 10,6 | 11,6 | 15,6 | 19,5 |
| k | max. | 1,3 | 1,8 | 2,1 | 2,4 | 3 | 3,2 | 3,6 | 4,8 | 6 |
| k | min. | 1,1 | 1,6 | 1,9 | 2,2 | 2,7 | 2,9 | 3,3 | 4,5 | 5,7 |
| n | nominal | 0,5 | 0,8 | 1 | 1,2 | 1,2 | 1,6 | 1,6 | 2 | 2,5 |
| n | max. | 0,7 | 1 | 1,2 | 1,51 | 1,51 | 1,91 | 1,91 | 2,31 | 2,81 |
| n | min. | 0,56 | 0,86 | 1,06 | 1,26 | 1,26 | 1,66 | 1,66 | 2,06 | 2,56 |
| r | min. | 0,1 | 0,1 | 0,1 | 0,2 | 0,2 | 0,25 | 0,25 | 0,4 | 0,4 |
| rf | approx. | 0,6 | 0,8 | 1 | 1,2 | 1,5 | 1,6 | 1,8 | 2,4 | 3 |
| t | min. | 0,5 | 0,7 | 0,8 | 1 | 1,2 | 1,3 | 1,4 | 1,9 | 2,4 |
| w | min. | 0,5 | 0,7 | 0,8 | 0,9 | 1,2 | 1,3 | 1,4 | 1,9 | 2,4 |
| y | Type C | 2 | 2,6 | 3,2 | 3,7 | 4,3 | 5 | 6 | 7,5 | 8 |
| y | Type F | 1,6 | 2,1 | 2,5 | 2,8 | 3,2 | 3,6 | 3,6 | 4,2 | 4,2 |
| Nominal | Type C min. | Type C max. | Type F min. | Type F max. | ST 2,2 | ST 2,9 | ST 3,5 | ST 4,2 | ST 4,8 | ST 5,5 | ST 6,3 | ST 8 | ST 9,5 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4,5 | 3,7 | 5,3 | 3,7 | 4,5 | + | ||||||||
| 6,5 | 5,7 | 7,3 | 5,7 | 6,5 | + | + | + | ||||||
| 9,5 | 8,7 | 10,3 | 8,7 | 9,5 | + | + | + | + | + | ||||
| 13 | 12,2 | 13,8 | 12,2 | 13 | + | + | + | + | + | + | + | ||
| 16 | 15,2 | 16,8 | 15,2 | 16 | + | + | + | + | + | + | + | + | + |
| 19 | 18,2 | 19,8 | 18,2 | 19 | + | + | + | + | + | + | + | + | |
| 22 | 21,2 | 22,8 | 20,7 | 22 | + | + | + | + | + | + | + | ||
| 25 | 24,2 | 25,8 | 23,7 | 25 | + | + | + | + | + | + | |||
| 32 | 30,7 | 33,3 | 30,7 | 32 | + | + | + | + | + | ||||
| 38 | 36,7 | 39,3 | 36,7 | 38 | + | + | + | ||||||
| 45 | 43,7 | 46,3 | 43,5 | 45 | + | + | |||||||
| 50 | 48,7 | 51,3 | 48,5 | 50 | + | + |
Materials
- Material and finish specified per RFQ — case-hardened carbon steel is the standard tapping body; state the host sheet and any plated/zinc finish requirement at quotation
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ISO 1481 Slotted Pan Head Tapping Screws) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
The trade-size matrix shows blanks — what does a blank mean for my order?
That length/thread pair is simply not a standard trade size. The "+" marks in the collected matrix are the standard's offered combinations: an ST 6,3 screw exists at l 13 and up, never at l 4,5, and the long lengths (l 45/50) appear only at ST 8/ST 9,5 where the shank can physically carry them. When a job lands between offered pairs, the honest options are the nearest offered length (the Type C/F min./max. tolerance bands — e.g. l 16 runs 15,2–16,8 — give a little latitude on both sides) or a different tapping form with its own matrix. Do not read a blank as "unavailable anywhere": this matrix is what the collected standard offers, and outsourced supply can source off-standard lengths — confirm the actual availability at quotation. Geometry across the family is otherwise fixed by the attribute table, so a nearest-length substitution does not change head or thread dimensions.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support