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CORPORATE ENGINEERING SPECIFICATION
CES 196
NITRIDING TREATMENT
Copyright 1996 as an unpublished trade secret. This document and
allinformation herein is the property of Valve & Controls
Division of Dresser Cond sur Noireau, FRANCEIndustries, Inc. It is
confidential and must not be made public or copied and
is subject to return upon demand.
Revisions Prepared By: F. COTTRAIT. Date: Feb, 1999
Rev. Description Date Approved By: G.ROUSSEAU .Date:
CES 196 REV. A
CES196.doc SHEET 1 OF 3
1. SCOPE
This procedure covers the technical requirements for nitriding
of valve parts.
2. MATERIALS
Materials covered by this specification are as follows :
Material grades Masoneilan materialcode number
ASTM A 487 Gr CA 6 NM class B
ASTM A 479 Ty 316
ASTM M 351 Gr CF 8M
193
163
163
3. MANUFACTURE
Martensitic stainless steel type CA 6 NM:This material shall be
stress relieving, prior to the nitriding treatment, after any ofthe
following operations :
Hard deposit Total on local quenching Welding.This stress
relieving may be omitted depending on parts weight, geometry
and
required dimension tolerance values.
The stress relieving treatment conditions must be :
Temperature :565C to 620C
Time : 3 hours
Austenitic stainless steel :A specific heat treatment of
austenitic stainless steel is not mandatory prior to the
nitriding treatment.
8/22/2019 Nitriding Ces-196 A
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Copyright 1996 as an unpublished trade secret. This document and
all information herein is the CES - 196 - REV. Aproperty of Valve
& Controls Division of Dresser Industries, Inc. It is
confidential and must not SHEET 2 OF 3be made public or copied and
is subject to return upon demand.
4. PART CLEANING
The parts will be free from scale, oxide, dirt, grease
etc...
5. NITRIDED AREAS
Unless otherwise specified on the part drawing, the surfaces are
fully nitrided (seeappendix No 1 for non nitrided permissible
areas).
6. NITRIDING TREATMENT REQUIREMENTS
6.1. White layer thickness :
The thickness of the white layer shall not exceed 0.013 mm.
6.2. Case depth and hardness :
The hardness and the case depth must be in such a way that the
surface hardness is
not less than 1000 HV 0.1.
6.3. Temperature limitations :
Maximum nitriding temperature must be at 15C below the minimum
temperature
of the final tempering treatment which is 565C for CA 6 NM
material.
7. DISTORTION - REMACHINING
All parts shall be properly supported in the nitriding furnace
to minimize distortion,see examples in appendix No 1.
Turning, grinding, polishing or any other remachining are not
acceptable afternitriding treatment.
The nitrited part dimensions must be in accordance with the
drawing requirements.
8. TESTS
Metallographic test may be performed, on coupons which are
representative of the
parts, to determine the white layer thickness.
The HV 0.1 hardness measurement can be performed on
representative samples or
on polished areas of the parts which must be prepared prior to
nitriding.
