Bolts/Nuts Material

Ohm-Srinivasulu. K

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Nov 24, 2009, 8:00:46 AM11/24/09

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HI,

I want to clarify a deviation request from Valve vendor,

As per the client specs,

For Bolting for Bonnet, Packing-box etc

All carbon steel or low alloy steel bolting shall be zinc plated(elctro-deposited), bichromated.

but vendor is proposing

Our proposal for A216 WCC Body (Non-Sour) as follows;

Body Studs & Nuts (21000 Series): A193 Gr.B7 / A194 Gr.2H zincplated

(without chromated)

Body Studs & Nuts (35002 Series): A193 Gr.B8 CL.1 / A194 Gr.8

Gland Studs & Nuts : A193 Gr.B8 CL.1 / A194 Gr.8

so my dout is in humid areas like Japan we need the bolts to be

Zincplated/bichromated to prevent white rust and in hot areas like

Qatar its not required.

Please confirm my understanding,

(As the specs were basically developed by JGC they specified as

zinc plated/bichromated)

Ohm-Srinivas

Sr. Piping Engg.

ohm guru namasivaya

Ramprasad Chari

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Nov 24, 2009, 10:56:19 PM11/24/09

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Zinc Electroplating is not a very durable/useful coating.Its thk is also around 15 microns only.Better ones are Cadmium Plating,Hot Dip galvanizing and Barium carbonate coating.

Regards

Aarpee

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Ohm-Srinivasulu. K

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Nov 25, 2009, 1:11:42 AM11/25/09

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RP,

Thanks, I should not deviate from company specs, what I can do is whether to approve the vendor proposal or not.

on A193 GR. B8 HDG may not stick unless zinc penetrates the passive oxide film on SS

Does A193 Gr. B7 material can be HDG?

ohm guru namasivaya

--- On Wed, 11/25/09, Ramprasad Chari <rampras...@gmail.com> wrote:

John Lock

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Nov 25, 2009, 1:49:59 AM11/25/09

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As ASTM A193 bolts are not stainless steel there is no issue with oxide film

Best regards,

John Lock

Quality & Classification Engineer

Pacific Deepwater Construction Ltd

cid:image002.jpg@01CA4F2E.75D71400

Cellular. +82 (0)10 4693 6282

Office Tel. +82 (0)55 631 9071

Office Fax. +82 (0) 631 7499

E-mail j.l...@pacificdrilling.com

P Before printing I think about the environment

Ramprasad Chari

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Nov 25, 2009, 4:45:00 AM11/25/09

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I was referring coating of HDG/Cd Plating on CS bolts only i.e.a193GRB7 and not on B8 bolts which are ss.HDG/Cd plating shall not be any issue on A193B7 bolts.

Regards

Aarpee

Ohm-Srinivasulu. K

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Nov 25, 2009, 7:50:16 AM11/25/09

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RP,Thanks,

Any one have idea about what will be cost difference incurred for HDG & Cadmium plating.