How to read an ASTM D2000 / SAE J200 line callout

ASTM D2000 (equivalent to SAE J200) is a classification system. Instead of naming a polymer or a trade name, a drawing or order states a line call-out that gives the performance a material must meet. Anyone whose material meets the call-out can supply it, so it is widely used in procurement. This guide reads one part at a time. The call-out decoder does the same on screen, suffixes included, and can also build a call-out for you.

The structure

A complete line call-out reads, for example:

ASTM D2000-18 M2HK714 A1-10 B38 C12 EF31 EO88 F15 Z1

The basic requirements, which are hardness, tensile strength, elongation, heat ageing and oil swell, are always in force unless a suffix replaces one of them. Only the suffixes you need should be listed. Specifying every available suffix is neither necessary nor wise, because each one adds a test and a cost.

M or no M: which units

• With M, tensile strength is in MPa, temperatures are in °C and tear strength is in kN/m. This is the form current editions use.
• Without M, the call-out belongs to the earlier inch-pound classification. The two tensile digits are then hundreds of psi (20 means 2000 psi, about 14 MPa), temperatures were in °F and tear strength was in ppi.

Mixing the two is a common error. A call-out written without M but with MPa digits asks for a different material from the one the writer meant.

Type and class letters

The first letter of the designation is the type. It sets the temperature of a 70-hour air-ageing test. After that ageing the material must stay within limits on the change in tensile strength, elongation and hardness. The general rule is a tensile change within ±30 %, an elongation change no worse than −50 % and a hardness change within ±15 points. The exact limits for each designation are in Table 6.

The second letter is the class. It limits volume swell after 70 hours in the reference oil, IRM 903, at the type temperature but not above 150 °C, which is the limit of the oil’s stability. IRM 902 and IRM 903 replaced ASTM Oil No. 2 and No. 3 under ASTM D5964. They are similar but not identical, so confirm which oil a buyer means.

Type and class are laboratory test levels. They are not service ratings and they say nothing about how a seal performs in your fluid, pressure or movement. Treat them as a way to rank materials, then test in the real conditions.

Material designations

Table 6 of the standard has one section for each designation that is in use. A letter pair that is not in this list is not a Table 6 designation.

The standard classifies by properties, not by polymer. A compound of another family that meets every limit in the section still conforms. If an application needs a particular polymer or cure system, state it next to the call-out. HK is the section for fluoroelastomers (FKM) and DH is the section that includes hydrogenated nitrile (HNBR). FEPM, perfluoroelastomer and PTFE have no section of their own in this list, so they are specified with a customer specification or a Z suffix. Black is assumed unless the designation is FC, FE, FK or GE, and a different colour often changes the properties.

Hardness and tensile digits

The three digits after the designation carry two numbers. The first digit is the Shore A hardness in tens, so 7 is 70 ± 5. The last two digits are the minimum tensile strength in MPa, so 14 is at least 14 MPa, and 05 is at least 5 MPa. Table 6 lists an elongation for each pair, so elongation does not appear in the call-out itself. Tensile in psi is shown in Table 6 for information only.

Grade numbers

Grade 1 means that only the basic requirements are compulsory and no suffix requirements are allowed. Any other grade allows suffixes. Each section of Table 6 lists the grade numbers that exist for each hardness and tensile pair, so a grade that is not listed there cannot be used. Writing grade 1 and then adding suffixes is a contradiction.

Suffix letters

Suffix numbers: test and temperature

The first number after the letter is the test method and time, from Table 5. The second number, when used, is the test temperature, from Table 4. Where the temperature number has two digits it is separated by a dash, so heat ageing at 250 °C is written A1-10 and low temperature at −75 °C is written F1-11. Writing A110 is a common slip.

The temperature numbers are the same for A, B, C, EA, EF, EO, G and K. The low-temperature suffix F has its own column. Temperatures follow ASTM Practice D1349.

A worked example, suffix by suffix

ASTM D2000-18 M2HK714 A1-10 B38 C12 EF31 EO88 F15 Z1 is a fluoroelastomer call-out. It reads: grade 2, designation HK (type H, class K), hardness 70 ± 5 Shore A, tensile at least 14 MPa, and seven suffix requirements.

The limit that each suffix must meet is in the HK section of Table 6, under the suffix and the grade. The call-out only says which test is run. Z1 is not defined by the standard at all, so the purchase document has to say what it means.

Common mistakes

• Leaving out the M and still meaning MPa and °C.
• Listing suffixes on a grade 1 call-out.
• Reading the type letter as a continuous service temperature. It is the temperature of a 70-hour ageing test.
• Writing A110 instead of A1-10, or a zero in place of the letter O in EO.
• Leaving out the year. Table 6 can differ between editions.
• Using a Z suffix without writing out the requirement and its test method.
• Assuming one call-out fits every fluid. Class and the EO, EF and EA suffixes test reference fluids, not your process fluid.

Writing a callout well

• Use only requirements you can test. Each suffix adds cost.
• Fill in the Z requirement for anything not covered, such as the specific fluid, the compression-set condition or a required approval.
• A call-out does not control the cure, the filler or the quality of manufacture. Add a polymer requirement if the application needs it.
• Call-outs say nothing about batch control. Add requirements for lot traceability and certificates.

Try it

Paste any call-out into the decoder to see each part, its test method and temperature, and any warnings. Examples to start from: a nitrile oil-seal call-out, an EPDM call-out and an older call-out without M. The builder tab writes a call-out from your choices, and the tables tab holds everything on this page in one place. The result can start a requirement in the requirement builder.

Sources and further reading

• ASTM D2000 and SAE J200. Tables 1 to 5 hold the type, class, suffix letter, temperature and test-method rules described here. Table 6 holds the limits for each designation and suffix, and is the part you must read in the current edition.
• ASTM D471 (fluid immersion), D573 and D865 (heat ageing), D395 (compression set), D1171 (ozone and weather), D2137, D1053 and D1329 (low temperature).