Frame and Cover for Gratings

[CWEngineer]

In the specs for a project it states that the Frame and cover for gratings shall be cast gray iron, ASTM A48/A 48M, Class 35B; cast ductile iron.

The contractor is trying to use Class 30.

Using ASTM A 48/A 48M - 03 (Standard Specifications for Gray Iron Casting), the minimum Tensile Strength for the Class 35B is 35 ksi and for the Class 30 is 30 ksi.

Basically from what I see the contractor is providing a Frame and Cover for Gratings of 5-ksi less than what is required.

This Frame and Cover for Gratings will be placed approximately 4 ft away from a Lake - where a vehicle is hopefully not expected to travel.

From your experience, would guys accept the Class 30 instead of the Class 35B? Or should I mandate the Class 35B be used?

 

[PEinVA]

What is the grating for? What are the stresses in the steel? What are the structural requirements for this grating outside of any specs?

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[CWEngineer]

Here is some updated information:

The spec calls out a cast iron grate. The contractor submitted an alternate, made of galvanized steel. The class ratings between cast iron and steel cannot be compared becasue they are not the same. The galvanized steel grate has an ASTM a-36 structural steel rating. It is traffic rated.

Per contractor this steel grade is pursuant to Caltrans Standards for strength.

 

[dicksewerrat]

Galvanized steel will start to rust in a couple years. The cast will not. Make him put in the cast as speced.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com