ISO 6789 Knowledge Center
One question per page: ISO 6789 editions, declarations of conformance, calibration certificates and what to ask for when ordering hand torque tools.
Articles
Overview
What is the difference between Part 1 and Part 2 of ISO 6789:2017?
Part 1 answers “Does this tool conform?” while Part 2 answers “How did this tool measure, and how much confidence can be placed in the results?”
Which edition should you follow when a customer specifies ISO 6789:2003?
When a customer explicitly specifies ISO 6789:2003, arrange the work under the 2003 edition and state that edition clearly in both the work request and the delivered documents.
Which torque tools does ISO 6789 cover?
ISO 6789 covers hand-operated indicating and setting torque tools used for controlled tightening.
Comparison
How does ISO 6789:2003 differ from the 2017 edition?
The 2017 edition split the single 2003 standard into two parts covering conformance requirements and traceable calibration, with changes to ranges, measurement procedures, and the reporting of results.
Documentation
Does calibration to ISO 6789 mean the laboratory is accredited?
No; a statement that calibration follows ISO 6789 and evidence of laboratory accreditation must be checked separately.
Is your document a declaration of conformance or a calibration certificate?
Check two things: does the document state whether the results fall within the permissible deviation, and whose uncertainty does it report?
How should you read an ISO 6789:2003 report, and what should you check?
A document has a clear basis if it identifies the 2003 edition and your requirements accept that edition.
Why did the document supplied with a new tool change from a “calibration certificate” to a “declaration of conformance”?
The 2017 edition separated tool conformance from traceable calibration of individual tools so that each document's name reflects the evidence it provides.
Do you need a calibration certificate if you already have a declaration of conformance?
It depends on the intended use: if you need traceable calibration results and measurement uncertainty for this individual tool, you need a Part 2 calibration certificate.
Is “ISO 6789” clear enough without a year or part number?
No; ask the supplier to add the year and, for the 2017 edition, specify Part 1, Part 2, or both.
More articles are added as they complete technical review.
Questions about the source text
How we read places in the ISO 6789 text where numbers, clause references or labels do not agree. These are our readings, not official ISO corrections.
What known issues are there in the text of ISO 6789:2017?
Our review of the original text identifies 5 issues in the 2017 edition: 2 confirmed errors, 2 suspected typographical errors, and 1 labeling inconsistency. None of these is an official ISO corrigendum.
ISO 6789:2017
Which capacity applies to fixed-adjustment tools in the ISO 6789-1 overloading test?
In 5.1.6 of ISO 6789-1:2017, nominal capacity is paired with D/E/F; based on the classification and the next sentence, we read this as the nominal capacity of fixed-adjustment Type II Classes B/E.
How should you read the class labels in ISO 6789-1 Clause 7.2’s example?
Clause 7.2 of ISO 6789-1:2017 assigns “nominal value” to A/D/G; we do not use that entry to apply fixed-adjustment nominal values to those classes, but select the target under 7.1 and check B/E nominal set values against 7.3.
How should you check the inconsistent uncertainty figures at 10 N·m in Annex A?
Recalculate from the components and formula, then cross-check the tables: the Annex A result at 10 N·m should be W = 1.160 %, rather than the 1.660 % printed in Table A.15.
Which clause should you consult when ISO 6789-2 Annex C cites C.5.4 for a certificate?
C.8 e) of ISO 6789-2:2017 cites C.5.4, which does not exist in the annex; consult C.5.2 for mean values and C.7 for uncertainty.
Why does Annex C label repeatability Type A but use a rectangular distribution?
Table C.1 of ISO 6789-2:2017 labels w_re Type A, but converts the difference between the readings in C.6 using a half-width and a rectangular distribution; we treat this as a labeling inconsistency open to interpretation and retain the formula for calculation.
ISO 6789:2003
Should the ISO 6789:2003 deviation example use 100 or 104?
Clause 6.5, EXAMPLE 1 of ISO 6789:2003 lists x_r1 = 100 N·m but uses 104 N·m in the subsequent calculation; only the latter reproduces −3.85 %, so we consider a misprint in the initial reference value more likely.