I need a grammar Nazi's help! (in Off-topic)

Is there anything grammatically wrong with this sentence?

"When calculating the K-factor for the main and remote strainers, if the total strainer surface area is used an unrealistic K-factor would be calculated."
(I think it needs a comma after "used", but technically why?)

What about this one?

Initially, the overall strainer system design including the main and the remote strainers together with a rough approximation of the required ductwork to connect the remote strainers to the sump were provided.

(I think it needs a comma after "design" and "strainers", am I wrong? If I am right, why?)

Your problem is clause upon clause.

Yes, item one needs the comma. Why? "If comma-then thus and so."

Yes, item two probably needs two commas, provided "including the main and the remote strainers" is meant to modify "overall strainer system design". Why? To separate the modifier from the rest of the sentence.

Item two has other problems, of course. Chief among them: "to connect the remote strainers to the sump" is (really) modifying "the required ductwork" which is why it's very hard to read what is intended -- presumably "Initially, the overall strainer system design together with a rough approximation of the required ductwork were provided." Move the verb to the front, check your modifying bits, and try to ditch the overly-difficult "together with".

Nazi isn't very nice. :P

Thanks Bast, I knew you'd be along. Having to proofread fop my very egotistical and hypersensitive boss. Everything I suggest is an attack on his character and his 30 years of experience. I hate the [SNK3R Edit: Non-PG]. He's the Nazi, not you Bast. :O)

FOR not FOP, argh!!!