Rail Inspections

[farhanjnawab]

We are a major Engineering Firm engaged in restoration of Naval Base in Jubail, Saudi Arabia.

BACKGROUND:

We have rails (136 RE AREA) laid 20 years ago and were in service lifting ship-lift trolleys in a Naval Dock Yard Project. In the due course of its service the coating of the rails is removed with the top surface being rusted and corroded bottom in some rails, so the rails are now subject to assessment and refurbishment.

QUERIES :

a. After sandblasting the rails, special profile check templates are being used by the third-party inspection agency to check the correctness of the profile and rail dimensions. Is there any standard for acceptance and rejection criteria for existing rails based on the actual dimensional checks?
b. The AREMA specs for new rails is very hard on the dimensions. If we go and compare the existing rail dimensions after sandblasting with AREMA tolerances, I think we'll end-up rejecting all these rails. Pls help....

 

[oneintheeye]

not sure what codes are applicable to you. Possibly the docks will have their own standards for replacing rails. For instance in UK here in freight yards it might be governed by one the operators specs. EWS (english, welsh and scottish railways) are one operator. I know they give a maintenence spec where the wear of the rail is stated at a limit before replacement. You will be unlilkely to meet any criteria for any agency for new rails as the tolerance at production will be tight. You could try looking into standards for track replacements using second hand rails?
You may need to get an experienced rail engineer involved who has experience with ship unloader rails. Suggest someone with no interest in recomending a replacement that is not neccessary.

 

[racookpe1978]

Many functional differences apply here between "common" railroad-type usage, and this "ship-movement" useage that MST be fully thought through BEFORE you decide what "typical" railroad profile rules aplly.

Yes, both applications use railroad rails. They both support steel wheels carrying heavy loads. Most evereything else is different:

Speed. Ship movement is very, very slow. A tolerance or bump or dip from corrosion in a train track being hit by a hundred cars rolling at 80 - 120 kph is very different than the same supporting a wheel rolling 1/2 kph.

On the other hand, a longer slump or low spot in the ship rails that a slow speed train would never notice will greatly "bend" and deflect the ship's hull as parts of the hull are alternatively supported, not supported, then raised up again. So the net "level" support for long ship's support structure is less tolerant of bends and waves that a low-speed train track is.

Higher loads are concentrated on the rail for longer periods of time since the ship will spend many days (weeks ?) sitting in one spot. On the other hand, these higher loads might only be moved 2 or three times a month.

Repair welds that will likely crack or break off under fatigue impact under thousands of impacts at a train's rapid speed might do just fine at low speeds and low accelerations.

 

[MikeHalloran]

I can't believe that a set of brand new rails wouldn't cost less than a thorough profile inspection and weld repair.



Mike Halloran
Pembroke Pines, FL, USA

 

[dhengr]

Google “AREMA” they are the American engineers who deal most with rails, they were AREA at one time, and have specs. on these things. Their profile criteria has more to do with rail head wear vs. wheel shape and wear, than with real structural deterioration of the rail, and your condition doesn’t have these billions of wheel contacts to produce this wear.

Racookpe, has it pretty much right, I have no disagreement with his comments, rather some additions. The real railroad rail loading condition is a wheel/rail bearing stress problem, under high speed impact, wear, fatigue and fracture are the issues. The real profile issue is the shape of the wheel tread and flange vs. the shape of the rail head. Your problem would be almost exclusively a wheel/rail bearing stress problem at low speeds, and that you not spread the rails. The tie condition, spacing and foundation conditions may be just as important for long duration concentrated loads under each boggy or truck. Structural condition of the rail should be pretty evident, a significant loss of rail head material, or rail web thickness or rail flange thickness and width. 136 Lb. AREA rail is one of the largest rails made. Look at the next size or so smaller, and compare its dimensions to your rail and investigate that smaller rail as adequate for your needs. Real rail profiling is generally a much different animal.

 

[Bobber1]

We had to strengthen some crane rail foundations for a local shipyard for some new, higher capacity cranes. The crane manufacturer gave us the tolerances they wanted.

What equipment will use the rails? Will it remain a ship-lift facility?

 

[RockEngineer]

The US Navy Facilities Engineering Command (NAVFAC) has the following document for rail inspection and certification which may give some ideas.

https://portal.navfac.navy.mil/port...tification detailed requirements 11142008.pdf