Isometric drawing 3

[flinana]

Hi,

I am an I&C engineer and we happen to have the problem that the detail engineering firma that has drawn all the isometrics has not taken into consideration the instrument data sheets and have drawn them wrong. My question if any instrumentation engineer has ever had to revise these isometrics as i am doing now. To me this has to be done by mechanical engineers.

thanks

 

[hydtools]

The drawings could be done by a mechanical designer. It doesn't take an engineer to correct bad drawings.

Do you not have recourse with the firm that created the drawings?

Ted

 

[flinana]

Thanks for answering I have spent a week correcting the isometrics. As an example of what was wrong was that although flowmeter data sheets indicated that the flowmeter was a mass flowmeter, on the isometrics they drew an orifice plate, so the pipe was built including an orifice plate, now we have to cut the pipe to fit the flowmeter. Manometers with saddle type seal were drawn with a 1/2 NPT nipple connection and so on. The engineering company that did these have been informed of these errors and the only way is to claim money for it
If I didn't check these drawings, no on else would and my instruments would not be mounted correctly.
Although these has to be done I have told my project manager that this is not the job of an I&C engineer but all to no avail. Fact is If I don't do it no one else will.

Frank

 

[Zapster]

Frank, what specifically was provided to the engineering company that made the ISOs. You state that you provided them with “data sheets.” Were these the manufacturer’s cut sheets that clearly shows the type of connection and the physical dimension of the instrument? If so, you are stuck fixing someone else’s mistakes because your supervisor “the project manger” may have realized that you are the best person to ensure that the corrections are accurate. Why is this a problem if you are getting paid for the work.

In contrast, if the “data sheets” only included ordering information without dimensions and connection types, the instrument folks did not provide enough information to the drafter and assumed that someone else would research the component. I can easily see a drafter blindly picking an automated block from their drawing program instead of contacting the manufacturer to get the dimensional information. The drafter would just assume that the installer would research the components physical dimensions. In this case, the drafter was not provided with enough information and may not have known that he was supposed to do the instruments engineer job of researching the specific components dimensions and connection type.

 

[hydtools]

Someone must have authorized the building of the hardware before a final drawing check and signoff. Not a good procedure.

Ted

 

[flinana]

The engineering company was provided with data sheets clearly stating the connection type and instrument type. For instance it was clearly stated that some flowmeters were mass flow meters and not an orifice plate. I am obviously the right person cause I have bought all the 1400 instruments of the plant but the problem is that doing this work at this stage leave me no time for checking other things like the DCS.

As always time is money so we had no choice but to go ahead with building the HW before even checking the drawings, and of course they were not checked in time due to lack of resources, personally all i checked were the P&IDs with up to 7 revisions as well as the instrument data sheets. If you are interested to know the plant is a Biodiesel production plant.

btw, thanks to you all for getting involved in this discussion.

 

[MikeHalloran]

Electing to go ahead with construction before the design is complete and checked is a "business decision".

The phrase "business decision" can be read as: "If things work out okay, the business majors get to wear their hero suits for a while. If things go badly, the engineers get all the, er, credit."

Costs associated with recovery from an unfortunate business decision are, of course, never formally associated with said decision.



Mike Halloran
Pembroke Pines, FL, USA

 

[flinana]

I couldnt agree more Mike. There is nothing I hate more than people trying to wear their hero suits or medals.