Yes i know , I should have just added steve to the list already/anyway.
Might have known he wouldnt want to be left out of a "class act".
Thought he must be on walkabout or "out drinking", because we hadnt heard from him yet on this one. Silly me.
> Hi Alejandroperezposada
>
> have you tried carrying out a warm and hot torque in addition to the
> initial torque?
> We use this on some process equipment with good results.
> Are the maintenance guys using a proper bolt torquing pattern? If the
> guys are simply working their way around the flange, then portions of
> the gasket may become overloaded and not recover properly, resulting in
> loose bolts.
> Have you checked the torque against whats in the manual? It would pay to
> check this as manuals sometimes have bad numbers in them.
> It would pay to check you are using the correct gasket; sometimes an
> alternative has been used which may not perform.
>
> In 90% of cases, I find a loose bolt was never tightened properly in the
> first place.
>
> Is this a new problem, one that has always existed or one that may have
> existed for some time but has only now been found?
>
>
> The likely causes of loose bolts are: inadequate torquing, nut backing
> off in service, insufficient gasket recovery/overcompression, bolt
> permanent stretch.
> It would pay to identify which of these is causing your problem.
>
> I suggest you confirm that the joint is being assembled properly before
> worrying about alternative bolts to those originally specified.
>
> Cheers
>
> Steve
> -----Original Message-----
> From: <a href="/group/PipingDesign/post?postID=FcwDJ8DJM6b9Kd8IcM4_GiQFmJN94t-zNScPgYKGAsEqYj9gU4_7eHgszFU7uOepYshv3Ea4ZV05IlAogP4T_ub3vtU">PipingDesign@yahoogroups.com</a> [mailto:<a href="/group/PipingDesign/post?postID=FcwDJ8DJM6b9Kd8IcM4_GiQFmJN94t-zNScPgYKGAsEqYj9gU4_7eHgszFU7uOepYshv3Ea4ZV05IlAogP4T_ub3vtU">PipingDesign@yahoogroups.com</a>]
> On Behalf Of Christopher Wright
> Sent: Wednesday, May 18, 2005 8:50 AM
> To: <a href="/group/PipingDesign/post?postID=FcwDJ8DJM6b9Kd8IcM4_GiQFmJN94t-zNScPgYKGAsEqYj9gU4_7eHgszFU7uOepYshv3Ea4ZV05IlAogP4T_ub3vtU">PipingDesign@yahoogroups.com</a>
> Subject: Re: [PipingDesign] Re: Bolting Loose
>
>
>
> On May 17, 2005, at 11:56 AM, alejandroperezposada wrote:
>
> > Is there a posibility in replace the ASTM A-193
> > GR B7 stud with a Machine Bolt Grade 8?
> why do you think you need to replace the bolt? You shouldn't be
> guessing about this. First, you *must* use ASME specifications for
> bolts anyway. Nylock bolts probably won't
>
> What are your bolting calculations telling you about the adequacy of
> the bolt?
> What does the joint look like?
> What size are the bolts and how long are they?
> Is there a gasket involved?
> I gather your loads are cyclic. Have you done any calculations to see
> if the temperature excursions are high enough to relax the preload in
> the bolt?
> What is the temperature and pressure range?
> How long does it take for the bolts to loosen (in terms of the load
> cycle time)?
> Have you set the preload?
> How certain are you that the bolts are tightened properly? Have you
> checked?
>
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw@skypoint.com | this distance" (last words of Gen.
> .......................................| John Sedgwick, Spotsylvania
> 1864)
> <a href="http://www.skypoint.com/~chrisw/">http://www.skypoint.com/~chrisw/</a>
>
>
>
>
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Received on Wed May 18 03:06:00 2005
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