Metal finishing Q&As since 1989

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Protective Grease on Flange Serration During Hot Dip Galvanizing

Dear sirs,

We are in Hot dip Galvanizing shop in Kuwait. We are to hot dip Galvanize some Fabricated Pipe Spools of Fire Water System. please suggest some HOT GREASE or that sort a material to apply on Serrations of Flange Raised face to maintain the Integrity of Flange Serrations.

G B SARMA
NBTC - Kuwait
2007

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2007

Sounds like you are asking if it's possible to mask off areas of steel in galvanizing.

If you find something that reliably works, please let us all know...

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

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July 8, 2009

Dear Geoff,

If we do not mask off the flange face or apply no protective grease on raised face from being galvanized, how to obtain the roughness as below,
------Pipe Flanges and Flanged Fittings
6.4.5.1 Tongue and Groove and Small Male and Female. The gasket contact surface finish shall not exceed 3.2 µm (125 µin.) roughness.
6.4.5.2 Ring Joint. The side wall surface finish of the gasket groove shall not exceed 1.6 µm (63 µin.) roughness.
6.4.5.3 Other Flange Facings. Either a serrated concentric or serrated spiral finish having a resultant surface finish from 3.2 to 6.3 µm (125 to 250 µin.) average roughness shall be furnished. The cutting tool employed should have an approximate 1.5 mm (0.06 in.) or larger radius, and there should be from 1.8 grooves/mm through 2.2 grooves/mm (45 grooves/in. through 55 grooves/in.)

Leo Cosco
- Nantong, China