IP 50: Determination of cone penetration of lubricating grease

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  • Method adopted/last revised: 2017
  • Method reapproved: None
  • REF/ISBN: IP50-2938621
  • Status: Current
  • First printed in STM books: April 2018


This method covers four procedures for measuring the consistency of lubricating greases by penetration of a standard cone. It includes procedures for the measurement of unworked, worked, prolonged worked, and block penetrations. Penetrations up to 475 may be measured. Undisturbed penetrations are described in the annex B.

NOTE 1 - The National Lubricating Grease Institute has classified greases according to their consistency as measured by the worked penetration. The classification is as follows:

Table 1: NLGI Grease classification

NLGI grade Worked penetration range

000 445 to 475

00400 to 430

0355 to 385

1310 to 340

2265 to 295

3220 to 250

4175 to 205

5130 to 160

685 to 115

NOTE 2 - The procedure for the measurement of penetration of petrolatum is described in Method ASTM D937-IP 179, Test for penetration of petrolatum.2

Unworked penetrations do not generally represent the consistency of greases in use as effectively as do worked penetrations. The latter are usually preferred for inspecting lubricating greases.

Penetrations of block greases can be obtained on those products which are sufficiently hard to hold their shape. These greases generally have penetrations below 85.

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