Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
ASME PALD 5b-1989 — Mechanical Screw Jacks Safety Standard Addenda (b)
📦 ASME/ANSI PALD-5b-1989 is the second Addenda to the ASME/ANSI PALD-5-1987 Mechanical Screw Jacks volume. It was approved by ANSI on October 13, 1989, and issued on November 30, 1989. Changes are marked by the margin note (b); changes from the first Addenda (5a) are marked (a). The revisions touch the Introduction, scope, proof load definition, design paragraphs, restructuring of the marking paragraphs, and testing paragraphs, making the safety requirements for mechanical screw jacks more consistent and verifiable in practice.
💡 Effect of an Addenda: PALD series revisions become effective three months after the Addenda issue date. Manufacturers, purchasers, and inspectors working with PALD-5-1987 should adopt this Addenda in parallel to keep products and practices compliant with the current requirements.
1. Summary of Changes 📌
| Page | Location | Change |
|---|---|---|
| 1 | Introduction — second paragraph of General | Revised |
| 2 | Section I (Scope) | Revised |
| 5 | Section 2 — definition of “proof load” | Revised |
| 5 | Para. 3.3 (design) | Revised |
| 6 | Para. 4.2 (identification) | Revised |
| 6 | Para. 4.3 | Deleted |
| 6 | Former para. 4.4 | Redesignated as 4.3 |
| 7–8 | Para. 5.1.1 (proof tests) | Revised |
| 7–8 | Section 6 (product instructions and warnings) | Penultimate paragraph revised |
| 8 | Para. 7.1.5 | Added |
⚠️ Watch the 4.3/4.4 renumbering: this Addenda deletes the former para. 4.3 and redesignates the former 4.4 as 4.3. When citing “PALD-5-1987, para. 4.3,” always confirm which version you reference to avoid mixing old and new numbers.
2. Proof Load Definition and Design Revisions 🔬
The “proof load” definition is revised in this Addenda, further clarifying its nature as a test load — greater than the rated capacity, applied centrally to the saddle to confirm structural integrity. The revision to design para. 3.3 relates directly to the construction of a mechanical screw jack: the strength, self-locking behavior, and fatigue reliability of the thread pair, crank/pawl mechanism, and base structure are the design core. After the revision, these requirements are better aligned with the acceptance criteria of the 5.1.1 proof tests, ensuring consistency across “design-test-acceptance.”
🚨 Self-locking is the safety-critical property of a screw jack. The revised design and test provisions jointly constrain thread strength and self-locking margin; any design that checks thread strength for static capacity alone while ignoring self-locking and fatigue does not conform to this volume.
3. Marking and Warning Requirements 🏷️
Section 4 was restructured in this Addenda: para. 4.2, as revised, requires identifying mark(s) of the original manufacturer or supplier with the date of manufacture traceable; the former 4.3 was deleted and the former 4.4 redesignated as 4.3. The revised penultimate paragraph of Section 6 completes the wording of warnings and product instructions, and the new para. 7.1.5 adds in-service inspection duties, extending the “inspect first, position correctly, center the load” discipline to a broader set of scenarios.
4. Impact on Manufacturers and Users 📊
- 🔍 Documentation sync: update design and instruction manuals to the current text of “base edition + 5a + 5b” and check the renumbering.
- 🔧 Test plans: update design qualification test plans to the revised proof load definition and para. 5.1.1.
- 📐 Marking verification: verify that rated capacity, manufacturer identification, and warning labels meet the revised Sections 4 and 6.
- 📋 Inspection updates: incorporate the new para. 7.1.5 into pre-use checks and periodic inspection procedures.
5. Frequently Asked Questions ❓
❓ Q: How does PALD-5b-1989 relate to 5a-1988?
A: 5b is the second Addenda after 5a; both are applied as replacement pages on top of the 1987 edition. The margin notes (a) and (b) identify where each Addenda made changes.
A: 5b is the second Addenda after 5a; both are applied as replacement pages on top of the 1987 edition. The margin notes (a) and (b) identify where each Addenda made changes.
🔍 Q: Why was para. 4.3 deleted and renumbered?
A: The committee consolidated marking requirements and removed duplication, deleting the old 4.3 and redesignating the former 4.4 as 4.3 to keep numbering continuous. Documents citing the old number must be updated.
A: The committee consolidated marking requirements and removed duplication, deleting the old 4.3 and redesignating the former 4.4 as 4.3 to keep numbering continuous. Documents citing the old number must be updated.
❓ Q: What is the testing impact of this Addenda?
A: The revised proof load definition and revised para. 5.1.1 make test load determination and acceptance more explicit; design qualification test plans should cite the revised current text.
A: The revised proof load definition and revised para. 5.1.1 make test load determination and acceptance more explicit; design qualification test plans should cite the revised current text.
❓ Q: When must manufacturers comply with this Addenda?
A: Under the PALD series rules, revisions take effect three months after the Addenda issue date (November 30, 1989, for this one); products manufactured thereafter must meet the current text.
A: Under the PALD series rules, revisions take effect three months after the Addenda issue date (November 30, 1989, for this one); products manufactured thereafter must meet the current text.
