clooney
Mechanical
- Jan 12, 2005
- 17
Are we always required to place an ANCHOR BLOCK at Above Ground (AG; hereinafter)to Underground (UG; hereinafter) transitions? I am assuming in order to completely isolate the movements of AG piping from UG piping, I would always have to recommend an Anchor Block. However; from what I have seen done in the field, not all AG/UG interfaces have anchor blocks. WHY NOT?
To get a definitive answer on displacements at AG/UG interface, I suppose I can model the UG piping and AG piping in CAESAR II based on provided soil data from Geotech people. And I have done this before. But often times, as a result of bad planning, clients come up with a several mile long buried pipeline plan profile (with inaccurate soil data) which terminates at an AG valve station or a metering station and they expect answers within days! because the contractor has leased his equipment and is waiting for the "go ahead" to start digging so he can get paid. Well, that is how it works in the middle east. Projects are infested with Bad Management, Bad MC's (or no MC at all), Clueless contractors, ..., etc.
Anyhow, when I have to come up with answers on such a short notice, do I really have to take the whole buried portion into consideration? OR is it O.K. to simplify the problem by studying the sags and rises of the profile and significant changes in direction (horiz.& vert.), and only take into account say a few hundred yards of the buried line between the AG terminal point and the point in UG where I feel the pipe is relatively restrained due to the shape of its profile (interacting with the soil)? Remember most of these lines are large bore Carbon Steel pipes and have design temperatures of around 180°F max. & installation temperatures of around 70°F unless it is summer time (considering solar rad. effects, installation temp can reach up to around 170°F). These lines are usually interconnecting gas transmission lines between different plants which are miles apart.
And what bothers me the most, is that what actually is built at the construction site is not necessarily what the "Approved for Construction" plans show. At least that has been my experience with most clients and contractors overseas. It makes me feel that perhaps it wasn't worth investing that many engineering hours trying to come up with somewhat realistic design loads for the Anchor Blocks. But let's not get side tracked, I want to concentrate on the technical aspects of making a good engineering decision, all things considered.
How do you guys approach this task? please, share your views, guide me,...,
Thanks guys
Farzad
To get a definitive answer on displacements at AG/UG interface, I suppose I can model the UG piping and AG piping in CAESAR II based on provided soil data from Geotech people. And I have done this before. But often times, as a result of bad planning, clients come up with a several mile long buried pipeline plan profile (with inaccurate soil data) which terminates at an AG valve station or a metering station and they expect answers within days! because the contractor has leased his equipment and is waiting for the "go ahead" to start digging so he can get paid. Well, that is how it works in the middle east. Projects are infested with Bad Management, Bad MC's (or no MC at all), Clueless contractors, ..., etc.
Anyhow, when I have to come up with answers on such a short notice, do I really have to take the whole buried portion into consideration? OR is it O.K. to simplify the problem by studying the sags and rises of the profile and significant changes in direction (horiz.& vert.), and only take into account say a few hundred yards of the buried line between the AG terminal point and the point in UG where I feel the pipe is relatively restrained due to the shape of its profile (interacting with the soil)? Remember most of these lines are large bore Carbon Steel pipes and have design temperatures of around 180°F max. & installation temperatures of around 70°F unless it is summer time (considering solar rad. effects, installation temp can reach up to around 170°F). These lines are usually interconnecting gas transmission lines between different plants which are miles apart.
And what bothers me the most, is that what actually is built at the construction site is not necessarily what the "Approved for Construction" plans show. At least that has been my experience with most clients and contractors overseas. It makes me feel that perhaps it wasn't worth investing that many engineering hours trying to come up with somewhat realistic design loads for the Anchor Blocks. But let's not get side tracked, I want to concentrate on the technical aspects of making a good engineering decision, all things considered.
How do you guys approach this task? please, share your views, guide me,...,
Thanks guys
Farzad
