Valve Magazine - Spring 2008

of the bulk hardness. Since most specifications do not list Vickers hardness requirements, the resulting Vickers hardness values must often be converted to another scale. ASTM E140 includes some hardness conversion tables that include Vickers values, but conversion tables do not exist for all materials and hardness ranges.

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Summary Hopefully, this information is not taken to indicate these testers should never be used. All of these devices have their place in production and field applications, as well as in laboratory environments. However, like all hardness testers, they need to be used with careful consideration of their capabilities and limitations. They really cannot be used to replace all of the bench-top hardness test devices. The main reason for this is that hardness conversion to the scales called out in specifications is not a simple and straightforward matter. A future column will cover the topic of hardness conversion issues in more detail. VM

347/347H

A696 GR C

SIZES:

F-91

7/8” to 24”

Cut to length 7/8” – 24” OD

ASTM/ASME/(Latest editions)

NACE MR01-75/DIN. 3. 1.B/EN 10204

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CIRCLE READER RESPONSE #159

Your Source for

Through Valve Leak Detection

Portable 5131-VPAC & Online 1278-VPAC

DON BUSH is a Principal Materials Engineer at

Emerson Process Management-Fisher Valve Divi-

sion ( www.emersonprocess.com). Reach him at

Don.Bush@Emerson.com. The author wishes to

acknowledge the assistance of Thomas Spence,

Director of Materials Engineering, Flowserve Cor-

poration ( www.flowserve.com).

For a Wide Range of Applications & Industries

REFERENCES:

¹. ASTM A⁸³³ Standard Practice for Indentation Hardness of Metallic Materials by Comparison Hardness, ASTM International, West Conshohocken, PA

². ASTM A⁹⁵⁶ Standard Test Method for Leeb Hardness Testing of Steel Products, ASTM International, West Conshohocken, PA

³. ASTM A¹⁰³⁸ Standard Practice for Portable Hardness Testing by the Ultrasonic Contact Impedance Method, ASTM International, West Conshohocken, PA

⁴. ASTM E¹⁴⁰ Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, and Scleroscope Hardness, ASTM International, West Conshohocken, PA