Technical Info Sheet #35
All galvanizers in the Benelux follow the requirements of the international quality standard EN-ISO 1461. Occasionally, foreign assignments require compliance with the American galvanizing standard ASTM A 123. Both standards have been drawn up and revised completely independently over many years. In principle, the process of hot-dip galvanizing is no different in the USA than in the EU. So the galvanized product will not differ from each other, only the standard text differs. For buyers who are unsure of their business, this is a stumbling block and they stick to one standard or the other. This paper makes a comparison between the two standards. This makes it clear where one should look for ASTM-
assignments extra should pay attention to.
Table 1 below details the comparison between EN ISO 1461 and ASTM A123. It should be noted that chapters and paragraphs are completely different in structure and for this reason the differences are classified by item. Thereafter, only those items are described where the ASTM A123 has additional requirements different from the ISO 1461.
The differences are presented in the English language in order to share them with parties who do not master the Dutch language.
| ITEM | EN-ISO 1461 | ASTM A 123 |
|---|---|---|
| Scope | general properties and test methods iron and steel articles fabricated not if continously galvanised not tube & pipe if automatic galvanised not products with specific standards not after - treatment not over-coating also centrifuged | requirements zinc coating test methods iron and steel products fabricated and unfabricated not wire, pipe & tube sheet if continously galvanised not tube & pipe if automatic galvanised not steel < 0,76 mm thickness not centrifuged (A153) |
| General requirements | content of zinc melt not chemical composition basis metal not surface condition basis metal | content of zinc melt chemical composition, grade or designation and type and degree of surface contamination of basis metal shall be supplied by purchaser not surface condition basis metal |
| Bath | total other elements <=1,5 mass% (excl. Tin and Iron) ISO 752, EN 1179/EN 13285 | not less than 98 % zinc by weight |
| Construction | according to ISO 14713-2 | according practices A143, A384, A385 |
| Additional info by the purchaser | composition and properties of basis metal presence of flame (laser, plasma)-cut surfaces indication of significant surfaces Identification of significant surfaces identification where unevennes are unacceptable written evidence of internal vents necessity of sample special pretreatment requirements necessity of special thickness after-treatments / over-coatings inspection arrangements | chemical composition, grade or designation and type and degree of surface contamination of basis metal shall be supplied by purchaser The method of selection and number of test articles shall be agreed upon (sampling plan (B602)) necessity of special coating thickness special test requirements surface condition of articles to be painted necessity of the use of masking materials leave the uncoated areas untreated in case of paint appearance criteria for Architecturally Exposed Structural Steel (AESS) any other project-specific aesthetic requirements |
| Info by the galvaniser | upon request: method of renovation uncoated areas certificate of compliance (ISO 10474) certificate of quality assurance | upon request certificate of compliance |
| Safety | to be provided by purchaser sufficient number of venting holes sufficient number of draining holes give consent to galv to provide holes | |
| Acceptance inspection | before products leave galvanizer assessment of appearance testing of thickness (if required by customer) adhesion test only by agreement. There is no suitable standard | by galvaniser or purchaser material shall be inspected at the galvanizer’s plant prior to shipment. Or otherwise by agreement assessment of appearance testing of thickness The specifying of tests for adhesion and embrittlement shall be subject to mutual agreement |
| Sampling thickness test | inspection lot = single order or single delivery load minimum # of articles see table 1 (identical to A 123) | inspection lot = single order or single delivery minimum # of articles see table (identical to ISO 1461) |
| Appearance | distance from > 1m free from; a. blisters (i.e. raised areas without solid metal beneath), b. roughness and sharp points (if it can cause injury), c. free from uncoated areas. considerations to aesthetics are secondary Agreement No cause for rejection; a. occurrence of lighter or darker areas b. some unevenness (e.g. Orange peel) c. Wet storage stain (if coating thickness still meets minimum value) d. Aesthetic effects (weld seepage) flux residues and zinc ash shall be removed where they can affect the intended use of the article or its corrosion resistance requirement (unless access in restricted). | Upon shipment from the galvanizing facility, galvanized articles shall be free from uncoated areas, blisters, flux deposits, and gross dross inclusions. Lumps, projections, globules, or heavy deposits of zinc which will interfere with the intended use of the material will not be permitted. Marks in the zinc coating caused by tongs or other items used in handling the article during the galvanizing operation shall not be cause for rejection appearance criteria for Architecturally Exposed Structural Steel (AESS) |
| Thickness measurement | test method accordingly ISO2808 & 2178 magnetic flux path method in case of dispute, gravimetric test magnetic method possible alternative : microscopic cross section not on cut surfaces not on areas < 10 mm from edges not on areas < 10 mm from flame-cut surfaces not on areas < 10 mm from corners | test method accordingly Practice E376 in case of dispute, magnetic test magnetic method possible alternative : stripping method / weighing before and after galvanising / microscopic cross section (=gravimetric test) |
| Reference area | number depending on shape & size of articles minimum three reference areas position depending on shape & size of articles 100 mm from edges Long articles: 100 mm from each end and in the middle whole cross section of the article Reference area at least 10 cm² minimum five test readings per area | minimum three reference areas widely dispersed over the volume of the specimen minimum five test readings per specimen |
| Thickness | mean coating thickness >= mean coating thickness table 3 and 4 mean value over ref area >= local coating thickness table 3 and 4 if not conform, 2x number of test articles | average coating thickness of all specimens > average table 1 average coating thickness of single specimens > average table 1 Minimum average thickness of coating for any individual specimen is one coating grade less than that required if not conform, 2x number of test articles individual measurement no cause of rejection |
| Renovation | total uncoated areas < 0,5% total surface of article each uncoated area < 10 cm² if larger, re-galvanize; Renovation; by zinc-rich paint, zinc-flake or zinc-paste products. Otherwise by zinc-alloy stick or by thermal zinc spraying including removal of scale, cleaning and pretreatment thickness of renovated areas ≥ 100 μm | total uncoated areas < 0,5% total surface of article or 256 cm²/ton each uncoated area < 25 mm in de kleinste dimensie length and width of the uncoated area shall be allowed to exceed 1 in[25 mm] in only one of the two dimensions. Surface conditions related to deficiencies related to design, detailing, or fabrication as addressed by Practice A385/A385M shall not be grounds for rejection. by zinc-rich paint Methods according to practice A780/A780M thickness minimum 75 μm and maximum 100 μm |
| Adhesion | no suitable standards exist does not need to be tested any test should be agreed prior to start if tests, only in significant areas cross-hatch test is more demanding than required | by cutting or prying with a stout knife no flaking off any test should be agreed prior to start |
| Embrittlement | not mentioned. Part of EN-ISO 14713-1 | only if evidence is present in accordance with Practice A143 |
| Certificate | upon request additionally certificate quality assurance (ISO9001) | upon request |
VISUAL PROPERTIES OF THE GALVANIZED PIECES
ISO 1461 states that the primary purpose of galvanizing is to protect the steel from corrosion. If additional aesthetic or decorative requirements are necessary, the customer should agree the degree of finishing with the galvanizer. There is no mention of aesthetic requirements in ASTM A123. Maximum attention should therefore be paid to the use of the materials.
The occurrence of dark or lighter gray spots or any unevenness on the surface is not a reason for rejection for the ISO 1461; also white spots caused by storage ( white rust) are not a reason for rejection as long as the zinc coating thickness remains above the specified minimum. Aesthetic problems due to welds that are not fully closed are also not grounds for rejection. There is no mention of these points in the ASTM A123 either. This should be agreed upon with the customer prior to order confirmation.
The ASTM A123 defines the following additional requirements:
Materials must not stick together after cooling. The zinc surface must not peel off under normal use. Thus, special attention should be given to mounting holes, wire contacts and the zinc surface in Si-rich material during exit inspection.
REQUIREMENTS BY ZINC COATING THICKNESS
The measurement and method of measuring zinc coating thickness is almost identical in both standards. There is only a difference in the required zinc coating thickness (see Table 2). “Local coating” and “Average one” has the same meaning : the average of the 5 measurements in a reference area. “Mean coating” and “Average all” also has the same meaning : the average of all measurements.
| 1461 | A123 | ||||
|---|---|---|---|---|---|
| Local coating | Mean coating | Average one | Average all | ||
| Steel (ISO1461) Structural shapes (A 123) | ≥ 6,4 mm >6 mm tot < 6,4 mm >4,8 mm tot ≤ 6 mm ≥3,2 mm tot ≤ 4,8 mm >3 mm tot <3,2 mm ≥1,6 mm tot ≤ 3 mm ≥ 1,5 mm tot <1,6 mm <1,5 mm | 70 70 55 55 55 45 45 35 | 85 85 70 70 70 55 55 45 | 85 65 65 65 60 60 35 35 | 100 75 75 75 65 65 45 45 |
| Pipe&tubing (A 123) | ≥ 6,4 mm >6 mm tot < 6,4 mm >4,8 mm tot ≤ 6 mm ≥3,2 mm tot ≤ 4,8 mm >3 mm tot <3,2 mm ≥1,6 mm tot ≤ 3 mm ≥ 1,5 mm tot <1,6 mm <1,5 mm | 70 70 55 55 55 45 45 35 | 85 85 70 70 70 55 55 45 | 65 65 65 65 35 35 35 35 | 75 75 75 75 45 45 45 45 |
| Steel (ISO 1461) Strip/Bar/Plate (A 123) | ≥ 16mm ≥ 6,4mm tot < 16mm >6mm tot < 6,4mm >4,8mm tot ≤ 6mm ≥3,2mm tot ≤ 4,8mm >3mm tot <3,2 mm ≥1,6mm tot ≤ 3mm ≥ 1,5 mm tot <1,6 mm <1,5 mm | 70 70 70 55 55 55 45 45 35 | 85 85 85 70 70 70 55 55 45 | 85 65 65 65 65 60 60 35 35 | 100 75 75 75 75 65 65 45 45 |
| Casting | ≥ 6,4mm ≥6mm tot < 6,4mm >4,8mm tot < 6mm ≥3,2mm tot < 4,8mm >3mm tot <3,2 mm ≥1,6mm tot ≤ 3mm ≥ 1,5 mm tot <1,6 mm <1,5 mm | 70 70 60 60 60 60 60 60 | 80 80 70 70 70 70 70 70 | 85 85 85 65 60 60 35 35 | 100 100 100 75 65 65 45 45 |
EN ISO 1461
Coatings applied by hot-dip galvanizing to iron and steel objects – Specifications and test methods.
ASTM A123
Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products
