Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
ASME B107.46-2004 — Stud, Screw, and Pipe Extractors: Safety Requirements
🔧 ASME B107.46-2004, published by the ASME B107 Committee, establishes performance and safety requirements for handheld screw and pipe extractors — commonly known as broken-screw or broken-bolt extractors. It supersedes the 1998 edition (B107.46M-1998) and belongs to the B107 family of standards for striking and struck tools. Extractors are specifically intended to remove broken screws, pipes, bolts, studs, and fittings from threaded openings, making them essential tools in mechanical repair and pipe maintenance work.
💡 An extractor works by reverse rotation: its tapered, fluted working end is driven into a pilot hole at the broken piece (or along its inner wall) so the splines/flutes bite into the broken part, and a wrench then rotates the extractor counter to the thread direction to wind the broken piece out. Reliable seating under impact is therefore the design key — and the focus of this Standard.
1. Scope and General Framework 📌
Section 1 (Scope) states that the Standard provides performance and safety requirements for handheld screw and pipe extractors intended specifically for removing broken screws, pipes, bolts, studs, and fittings from threaded openings. Importantly, it covers only those designs that require striking of the extractor to seat it properly in the broken pipe or fastener. Designs that do not require striking — such as the ground thread extractor, which seats by being screwed directly in — are explicitly outside the scope.
Consistent with the rest of the B107 series, this Standard:
- Serves as a guide in selecting, testing, and using the tools covered;
- Does not specify manufacturing details, only safety-relevant design requirements;
- Is intended to guide the development of manuals, posters, and safe-practice training;
- May be used by state authorities or other regulatory bodies in formulating laws or regulations.
⚠️ Before choosing an extractor, verify that its design is the “strike-to-seat” type. Using a no-strike ground thread extractor as if it were a striking type (or vice versa) will fail to remove the broken part and may damage the tool or injure the operator.
2. Classification and Typical Designs 🔩
Section 2 (Classification) lists four generally recognized styles of extractors (illustrated in Figs. 1 through 4 of the Standard). The names are those commonly recognized in the trade, and the Standard states that the styles covered are not limited to those listed or illustrated:
| Type | Name | Construction Feature | Typical Usage |
|---|---|---|---|
| Type I | Multi-Spline Extractor | Multi-spline (multi-flute) working end | Large engagement area; suited to harder broken parts or regular fracture faces |
| Type II | Spiral Flute Extractor | Spiral flute working end | Spiral flutes clear chips and give smooth withdrawal; the most universal style |
| Type III | Straight Flute Extractor | Straight flute working end | Simple to make, stiff working end; suited to most general jobs |
| Type IV | Tapered Flute Extractor | Tapered flute working end | Taper aids wedge seating under impact; tolerant of hole-size variation |
In every style, the core idea is the same: the working end is tapered (or conical) so that, once driven in, the extractor locks into the broken part and then rotates it out in the direction opposite to its thread. Section 4 (Definitions) and Figs. 1–4 give uniform names for the striking end, working end, and flute forms.
🚨 The extractor must match the size of the broken part: too small and it will slip and fail to bite; too large and it can swell and crack the broken part inside the hole. Always follow the manufacturer’s extractor-size vs. thread-size cross-reference table.
3. Technical Requirements and the Impact Test 🧪
Section 5 (Requirements) covers material and heat-treatment requirements. An extractor sustains a combined “impact + high torque” duty: the working end must be hard enough to bite into the broken part, while the tool as a whole must stay tough enough to avoid brittle fracture. Hardness is verified by Rockwell testing per ASTM E18, and heat treatment is the key manufacturing control. Section 6 (Tests) centers on the impact test (Table 1 gives the impact test parameters):
- Test object: representative extractor sizes are sampled by type for verification;
- Test method: impacts of specified energy are applied to the extractor, simulating the strike-to-seat operation;
- Acceptance: after impact, the working end and body must show no cracks, chips, or permanent distortion that prevents functioning, and must retain their gripping capability.
4. Safety Requirements and Limitations of Use 🛠️
- Eye protection: broken parts and chips can fly during striking; operators must wear eye and face protection per ANSI Z87.1;
- Correct striking: strike the striking end only with a suitable hammer; never re-strike an already seated extractor (this can shatter the flutes);
- Drill a pilot hole first: use a center drill or twist drill for solid broken parts; follow the manufacturer’s guidance on hole depth and diameter;
- Lubrication: apply penetrating oil to the flutes before withdrawal to reduce torque and flute wear substantially;
- Inspection: discard extractors with worn, rolled, or cracked flutes — they cannot be safely reconditioned;
- Marking: safety signs and size identification per ANSI Z535.4.
5. Engineering Practice Essentials ⚙️
- Selection workflow: assess broken-part material and fracture location → decide whether drilling is needed → select extractor type and size from thread size → confirm it is the strike-to-seat design;
- Set management: maintain multi-size extractor sets with a posted cross-reference chart to prevent field misuse;
- Torque control: apply torque gradually with a wrench; stop immediately on slippage, reseat, and try again;
- Procurement acceptance: request impact test and hardness data from suppliers to confirm conformance with this Standard.
6. Frequently Asked Questions ❓
❓ Q: Why do some extractors not need striking?
A: Ground thread extractors seat themselves by screwing in directly and are therefore outside the B107.46 scope. Always confirm the construction type when purchasing.
A: Ground thread extractors seat themselves by screwing in directly and are therefore outside the B107.46 scope. Always confirm the construction type when purchasing.
❓ Q: Which of the four types is the best?
A: There is no absolute best. Multi-spline types give large engagement for harder parts; spiral flute types clear chips and are the most universal; straight flute types are stiff and simple; tapered flute types tolerate hole-size variation. Choose by duty.
A: There is no absolute best. Multi-spline types give large engagement for harder parts; spiral flute types clear chips and are the most universal; straight flute types are stiff and simple; tapered flute types tolerate hole-size variation. Choose by duty.
❓ Q: What should I do if the extractor keeps slipping?
A: First check size matching and whether the pilot hole is too deep or too large; confirm the flutes are not worn; if needed, use the next larger extractor or apply penetrating oil before retrying.
A: First check size matching and whether the pilot hole is too deep or too large; confirm the flutes are not worn; if needed, use the next larger extractor or apply penetrating oil before retrying.
🔍 Q: Which documents does the Standard reference?
A: Chiefly ANSI Z87.1 (eye and face protection), ANSI Z535.4 (product safety signs and labels), ASTM E18 (Rockwell hardness), and the HTI Guide to Hand Tools — Selection, Safety Tips, Proper Use and Care.
A: Chiefly ANSI Z87.1 (eye and face protection), ANSI Z535.4 (product safety signs and labels), ASTM E18 (Rockwell hardness), and the HTI Guide to Hand Tools — Selection, Safety Tips, Proper Use and Care.
