Making Asbuilt drawings of an existing Plant 1

[zeney]

I have to produce asbuilt drawings of an existing plant. One method is to get hold of a measuring tape and start measurement from one end manually. But lot of pipes may be difficult to access and this method seems very tedious, inaccurate and time consuming.
I want to ask what is the standard practice in this regard. Are there other methods of measuring pipe lengths, location of equipment etc.? Are there some instruments available for this purpose? Are there some articles available online on this subject?

Thanks

Zen

 

[JLSeagull]

Laser scan.

 

[SeanB]

What are you as-building - P&ID's or isometrics? Seeing as you are talking about using a measuring tape I guess you must be talking isometrics. If it is P&ID's you don't need a measuring tape. Take your existing drawings are start walking each line. If something in the field doesn't match what is on the P&ID, mark it up.

 

[JLSeagull]

I agree with SeanB regarding walking the plant and marking P&ID's. The laser scan applies if you need 3D dimensional plans. These plans can be used to interface the 3D CAD modeling software for dimensional control etc.

http://www.hi-cad.com/

 

[zeney]

thanks for reply. I mean to make isometrics and orthographic drawings. We made all the isometrics and layout drawings.Now that it is ready there are many minor and a few big changes which were not documented properly. So i want to check all the dimensions of pipes etc. Doing it with simple measuring tape seems time consuming. I saw a laser tape which throws laser in three directions in a plane at 90 deg. Civil engineers use total station or some thing like that. I wanted to know which instruments can be used to speedup and simplify the work?

Zeni

 

[Zapster]

zeney,

What tolerance are you trying to achieve?

 

[zeney]

I would like to be as close to actual as REASONABLY and PRACTICALLY possible but I don't have any specific tolerance in my mind.

Zeni

 

[tickle]

Seems like a laser scan is the way to go, I think the tolerance is pretty good

 

[zeney]

Laser scan is definitely a solution but it is quite expensive and may be more than I require here. As far as I know laser scanning would give a point cloud which would be used to produce 3D model. All I need is some suitable distance measuring device (hand held or tripod mounted) which could read distances remotely with some accuracy, speed and ease.

 

[VikingUK]

I had this problem a while back and it's a pain. My advice, if your budget can stretch, is to get a specialist company in to do it.

 

[dcasto]

I have to ask, what could one ever do with iso's after the fact?

If its for MI, used risk based and you don't need to find a single 1/4" spot on some line up in the piperack every year, so iso won't help their. If you need a stress analysis, then do it for that line.

The only place I've used iso's after the plant was in full operation was the cold box, and then the best estimates came from the 3 d plastic model of the things.

 

[pennpiper]

The last commenter asked.
"I have to ask, what could one ever do with iso's after the fact?"

In my career I was involved in three "Fire Rebuild" projects.

With each case, within five days after the fire I was at the site and began pulling the P&ID's and all the piping isometrics. Within fifteen days I had all the isometrics (that needed to be rebuilt) in the hands of a fabrication shop for bid and in the hands of my home office for material take-off of all material and for the preparation of RFQs for any non-fab shop material (Spring Hangers, etc) Fire rebuilds are the real "Fast Track" projects.

I believe that Client operating facilities (Refineries, Chemical Plants, etc) subject to damage by fire should keep P&IDs up to date for all modifications.

For rebuilding the piping they should keep all the isometrics.

 

[786392]

I do agree and share that
on record'as built' isometrics are really imortant reference doc

At my previous employers in early 90's I came across similar post fire rehablitation effort& these proved helpful/much relied upon docs.

As regards eloctronic data archiving if this is fool proof, virus proof system alongwith sufficient back-ups;

then situation may/should be reviewed on case to case basis.

Best Regards
Qalander(Chem)

 

[zeney]

I think if there is a need to keep the isometrics of an existing plant, then it should be updated information and not outdated and misleading. Why one need to have isometrics of an existing plant is an other question. May be to replicate it at some other place or to improve the design, any bodies guess.