Are shop drawings really "shop" drawings? 1

[MotorCity]

As technology has advanced and there is now software for everything, I question whether the shop drawings I receive are really "shop" drawings. Said another way, are the drawings I review as an engineer really the drawings that the guys in the shop are hovering over on a table to layout and construct my widgets? I say no.

I review alot of shop drawings, but mostly steel fabrication shop drawings. Nevertheless, the same question is posed for the review of any submittal......rebar, wood truss, etc.

I know that most (all) of the steel is fabricated by loading a program into equipment that automatically cuts members, drills holes, etc. and I realize that a smaller percentage of the work is hands on (i.e. shop welds). I feel like alot of the steel shop drawings I review are generated for the sole purpose of my review and not really used in the "shop". I say this because, quite frankly, they lack alot of the detail needed if these widgets were going to be fabricated only using the shop drawings.

In general, I despise shop drawing review because it can be tedious work that serves no purpose other than as a favor to the contractor to catch any last minute errors. Seems like my review of shop drawings is in vein at times and everything could get built whether I review them or not.

 

[KootK]

The only shop drawings that I've been involved in producing are precast shop drawings. There, the review drawings were most definitely not true shop drawings. Our goal would be to anticipate what the design team needs to review for the improve the odds of a successful outcome for the project. We would happily share the real shop drawings if desired but, in many cases, the full set of those those wouldn't available until erection was nearly complete.

The stuff that I would target would be:

1) Necessary dimensions.

2) Details that show geometry and connections but little of accuracy internally within members.

3) Confirmation of design criteria.

4) Stuff needed for erection and handling.

5) Member layouts.

...

 

[dik]

The ones I encounter for steel fabrication are definitely used in the shop. Not all the E type drawings, but the 'parts' stipulated on them are used. Sometimes I have to seal these, too because enough information is not contained in the E drawings.

I do a cursory check of dimensions, but clearly stipulate that detailed dimensions have not been verified.

-----*****-----

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JedClampett]

In general, I despise shop drawing review because it can be tedious work that serves no purpose other than as a favor to the contractor to catch any last minute errors. Seems like my review of shop drawings is in vein at times and everything could get built whether I review them or not.

I guess I'm a glass half full kind of guy, but I view them as my last chance to validate my design. On occasion, I've reviewed the design during the shop drawing phase and adjusted it. It's pretty much like "Oh bleep, the C12 x 20.7 needs to be a C12 x 25!" I change it on the shop drawing. Does it result in a change order? Sometimes. But I'd much rather have that conversation than the bouncy beam one.
And I've also found fabricator errors. Once again, fixing them in a submittal is better than trying to justify an inadequate member. And there will be pressure to justify that member.

 

[dik]

and occasionally engineering errors... an HSS portal frame a few months ago stipulated end moments that were greater than the section capacity, with these eventually becoming compression elements, to boot.

It was accommodated by a simple phone call to the EOR.

-----*****-----

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[DrZoidberWoop]

Engineer for a structural steel fabricator here. I'm not in the "widget" business, but the shop drawings I review are 100% the ones they use on the fab floor. I can walk 100 feet from my office to the shop and verify. My company takes on a lot of fabrication jobs that can't be cnc automated, so the review is necessary.

I approach shop drawing review as a method to insulate the company's reputation from shoddy detailing. As the detailing jobs are offshored more and more to the Philippines, India, or wherever, the shop drawing quality has taken a sharp dive. There are not many "grey-hairs" in the American steel detailing business anymore. It is now comprised mostly of glorified 3D modelers, who sometimes don't appreciate the ramifications of their poor detailing.

 

[Aesur]

DrZoidberWoop said pretty much what I was going to say about the quality of shop drawings as of late, in fact I am contemplating updating my contracts to state you get one shop drawing review for each item, any additional is add services at this point. I have had a few steel and wood truss shop drawings rejected (yes they were that bad) 7+ times.

To clarify a bit, the items missing were keynotes and detail notes that indicated drag loading, added loading, high snow loading and sometimes just flat out missing members.

Edit: it is also my understanding that the fabricators rarely see the actual structural drawings and rely on the contractor to provide this information, which is IMO the breakdown in the system many times.

 

[dik]

I take that a step further and that I stipulate the work has to conform to AESS 2 to AESS 4, depending on the work. Public stairs, guardrails and handrails to AESS 4. This it to help avoid 'ugly work'.

-----*****-----

So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Brad805]

This will depend on the market you work in and the level of automation of the supplier. I work with some steel fabricators that have heavily invested into automation, but others are still old school. The old school guys do all the layout from the part dwgs. You will find wood truss guys that still try to make a buck with very low tech equipment as well. Again, they need part dwgs, but what they need is not generally supplied to the consultant. What you may be seeing is the result of the shift in our industry. Some review shops, other do not do much more than apply their stamp. We sent out a 50page set of dwgs and all the tech could comment about was a few dowels seemed 1/16" out of alignment. Another old dog reviewer on another project not long ago had many useful comments. The old dog reviews are far and few between. This combined with the turn around time for shop drawing reviews means some send you only partially complete dwgs.

Having a better understanding of the modeling process the supplier uses can also be very helpful. If you know your supplier is using Tekla or another similar detailing package to model their components, you can ask for a model. Most have options to share models for viewing purposes. You may need to spend a bit of time learning how to navigate the viewer. If it appears correct in the model, that is what the part dwgs will show. You do not need to spend anytime checking dimensions as the software looks after that. It is very difficult to cheat dimensions in Tekla. Now that does not hold true for Revit. It is far too easy to supplement your crap model in Revit with 2D cad data that may or may not be correct. That said, most detailers quickly learn that their mistakes cost someone money and they need to pay attention. There is little room in shop dwgs for sloppy drafting.

 

[DrZoidberWoop]

Here is a simple example of why shop drawing review is necessary for me:

There are some elements of connection design that are not necessarily "engineered," and I will only see them in the review stage. Things like pour-stops and minor attachments are usually resolved at the detailer's discretion. The image below shows a viable connection btw a plate to a support beam. The problem lays with the weld the detailer selected. It requires weld prep for a CJP on a 3/8" plate. It doesn't look like a big deal on paper, but when you notice this is applied over thousands of feet all over a given job, it translates to big money via shop labor. Little items like this can add up quickly and sink a job's profitability, as well as piss off the client.

 

[human909]

I used to produce 'shop' drawings so I know a thing or two about it, or at least how it is done here in AUS. Labour is expensive here so automation is preferred though still not widespread except in profile cutting of plates.

The shop drawaing are exactly what the fabricator sees on their workbench. That is the point of them. Plates for cleats etc are almost always profile (normally laser) cut to .DXF files. Structural members sometimes go through a beam line which cuts, drills and sometimes copes the beam, .NC files are sometimes supplied for this purpose. In either case if electronic files are supplied, the drawings still take precedence and it is up to the fabricator to get it right. (Though certainly for .DXF and mostly for .NC the translation is 100% accurate.)

Some places even have automation of cleat placement in automated production lines. But that is still a minority of fabricators.


We do some of our own fabrication in our workshop that is 50m from my office. But generally not for bulk structural steel, it is generally smaller stuff, vessels or mechanical items.