In the future of RYPN thread I discussed the idea that the way we do things over time changes and what do we do to preserve the old techniques. Here is an example of how things have changed. In the current 49 CFR Part 230.36 states


§ 230.36 Hydrostatic testing of boilers.
(a) Time of test. The locomotive owner and/or operator shall hydrostatically test every boiler at the following times:
(1) During the 1472 service day inspection, and at every annual inspection thereafter;
(2) After making any alteration to the boiler;
(3) After installing a flush patch on an unstayed portion of the boiler; and
(4) After any riveting on an unstayed portion of the boiler.
(b) Method of testing. The metal temperature of the boiler shall be between 70 degrees Fahrenheit and 120 degrees Fahrenheit each time it is subjected to any hydrostatic pressure. Hydrostatic testing required by these rules shall be conducted at 25 percent above the MAWP.
(c) Internal inspection. An internal inspection of the boiler shall be conducted following any hydrostatic test where the pressure exceeds MAWP.

The southern Pacific rules in 1916 state

The Southern Pacific Company's Rules for hydro testing a boiler are interesting.
The rules effective July 1, 1916 states.

25 hydrostatic test

1. In making hydro test test the boiler must be filled with hot water or if filled with cold water it must be heated to 150 or 200 degrees before pressure is applied. All safety valves must be taken off and holes capped or plugged before making test. If pressure pipe from pump is connected to blow off cocks, care must be taken to know that the cocks are open before applying pressure In making test, two gauges must be used one connected to pressure line and the other on the boiler.
2. Stationary and portable boilers carrying a pressure of 100 pounds or more per square inch must be tested to 25 per cent. above the regular pressure at each annual test or before being placed in service. Boilers carrying less than 100 pounds pressure must must be tested to an excess of 25 pounds above the working pressure once each year or before being placed in service.
3. All classes of stationary and portable boilers and air reservoirs must be inspected and thoroughly tested by hydrostatic pressure once every year, making out report of such tests on Form CS-4422.

Notice the temperature change in the two procedures. It is an interesting change. The question I have when I see such things is what levels of thinking were in place then vs. now. What do we know now we did not know then or more importantly have we lost a point of knowledge? While the answer here is a better understanding of metallurgy it is interesting to see the differences. but the bigger question is when you have an older technique and a newer technique what do you consider in choosing a technique, familiarty, ease, or other factors.

Robby Peartree

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The temperature change is interesting with relationship to time and what we knew and what we consider safe.. Many of us have seen pictures of hydros done too cold (such as UP 8444 in the 1970's that blew side sheets) and that is because of the ductile/brittle transition zone for material failure. The 70 degree is nice for the tester but depending on your steel it begins to push the Ductile brittle transition zones. 120 degrees (All temps Fahrenheit) while uncomfortable for most people is seen every summer in certain parts of the country. Furthermore if the vessel is truly full, and water is a incompressible fluid it does not take much water to reach maximum hydrostatic pressure.

It is important to consider the time and era of 1916. A 100 years ago WWI was in full swing in Europe. The locomotive appliance and inspection act was still new. Locomotives such as the 2472, 786, 5021 and others were still in the future. The book is a moment in technological time. The procedures and techniques are interesting to read. How things and why things have changed is a study in its self It tells us a lot about who we are and how our techniques and abilities evolve over time.



Robby Peartree

I agree with the reasoning that Mr. Anderson espouses. I hadn’t considered the safety concerns of a higher test temperature but once articulated it stands to reason.

I am not sure that the temperature dependent brittle-ductile transition function is applicable in this situation. For example the transition typically occurs well below 0 degree F in mild steels with a carbon content at .18%. The transition is also examined, in laboratory settings, using the Charpy test procedure. This impact test is dramatically different from slowly bringing a vessel to test pressure in a hydrostatic test. Or at least the test pressure should be brought up slowly if executed correctly. Time rate of change of stress is significant in this situation.

Two empirical arguments against the brittle-ductile transition being of primary concern are cold pressure vessels and cold forming steel in the construction or repair of a boiler. In the first we are comfortable with the air receivers of a locomotive being pressurized in the winter. We don’t provide heat to the reservoirs nor should we. In the second we roll sheets by exceeding the modulus of elasticity at room temperature and in the case of riveted structures we aren’t obligated to normalize through heat treatment for grain structure following forming. The lack of heat treatment doesn’t seem to contravene established practice.

I do believe that the academic examination of why thought the process changes with time of great merit. It helps us to understand how decisions are made and why. Historical examination of engineering allows us to build a better product.

Dear Mr. Peartree,
Are there pictures of this incident available and is there any information or commentary about this? Though unfortunate, it would be something to know a little more about and study.
It is nice to do hydrostatic tests in the 25-30C range bringing up and releasing pressure slowly.
Thank you.

Anecdotally, when I was young and just getting into the preservation field I was witness to a serial failure of staybolts. The engine in question was under a warm water hydro and if memory serves the goal was 150% of MWAP. Anyway, on the way up a row of bolts failed. Sounded like a machine gun. My opinion at the time was” WOW!” Examination which followed revealed that there was considerable corrosion and reduction of supporting area in the bolts. Because of this the unit stress was higher for the bolts and they let go until the pressure had fallen in the boiler. Needless to say there was a lot of bolt replacement in short order. So there would appear to be other modes of failure then just excursion into the brittle-ductile transition zone.

This is not an indictment of Mr. Peartree's assessment of the 8444 incident. About that I have no information and hence no opinion.

I recall hearing of an incident of an engine out west that was hydroed where the pressure was brought up way too quickly and went way over MAWP if memory serves. I think it was done by a fire department pumper.
Warm, slow and easy both ways on a squeeze.

As one who has attended a number of meetings on the subject, may I propose to the discussion that the failures our industry has seen were a result of air pockets trapped in the water that collapsed or burst, which then caused such a high impact or explosion/implosion in a localized area that the steel failed. Water above 70 degrees, but way less than 200 is more fluid and less prone to trapping or encasing air pockets that can cause water hammer or other related damage. I believe strongly that in the case of the 8444 and one other unnamed locomotive in the west, that in both cases the cause and effect were the same. Though off topic, the landing of the US Airways aircraft on the Hudson was largely successful as the water was so cold and dense that it was easier to land on the water. Conversely, had the landing occurred in much warmer, less compacted and less dense water such as that found in the Bahamas, the end outcome may not have been the same. Water density and structure as a result of temperature is critical. Even when the spread is only 50 degrees F.

Kindly,

The way I understand it is, if you fill the boiler with cold water and pressurize it with no air pockets and then let it sit overnight in a warm shop. The water expands and greatly increases the pressure.

I suggest reading Mechanical Metallurgy by George E. Deter which I used for this post. Chapter 14 begins with "During WWII a great deal of attention was directed to the brittle failure of Liberty Ships and T-2 tankers. Some of these ships broke completely while in other instances, the failure did not completely disable the ship. Most failures occurred during the winter months. Failures occurred both when the ships were in heavy seas and when they were anchored at dock." At the end of the paragraph it states While the brittle failure of ships concentrated great attention to brittle failure in mild steel, it is important to understand that this is not the only application where brittle fracture is a problem. Brittle failures in tanks, pressure vessels, pipelines, and bridges have been documented as far back as the year 1886."

Mild steels with little contamination have has a low transition temperature. The addition Triaxial stress, low temperature, and a high strain rate or rapid loading rate can all cause a brittle failure. The Charpy V notch test is typically used to measure this. It is a hammer on a swing that hits a notched sample to produce a fractured surface. While the temperature for Ductile/Brittle transition temperatures vary dependent upon elemental makeup. Every 0.1 percent carbon raised the transition temp 25 F. Manganese lowered the transition temp 10 F for every 0.1%. Oxygen is has a great effect on toughness(ability to absorb energy). In experiments where the percent oxygen was raised from 0.001 to 0.057% the temperature increased by 5 to 650 F. But it is not only the amount of impurities but their orientation to stress and location with in the microstructure that also contribute.

My point about the change is we technology wise have come a long way in metallurgy. Yet we deal with boilers and other items built before this was completely understood. Studies of titanic steel shows that it was susceptible to brittle failure and the damage from the ice berg was worse due to the elemental conditions. The temperatures the Southern Pacific used in 1916 may have been their way to address this issue without realizing the cause? I bring up cold hydros and disastrous results because they still can happen.I understand the 8444 incident happened in a winter hydro test with limited heat available. Some food for thoughts on causes of failed hydros, how does a self leveling liquid collect an air pocket of sufficient size to do the damage? Perhaps over pressurization or a load shock may have contributed to any failure but have gone unrecognized? Charlie Williams the ICC/FRA inspector who inspected SP 3420 before he retired told me once if you want to impress an inspector do the hydro with a hand pump. It proves two things; first that all the air is gone and two that the boiler is tight. Doing a test with a pump it is easier to mask a problem or do damage to the boiler from over pressurization

It is amazing the thermal expansion a locomotive boiler undergoes from room temperature to operating pressure. The lower the temperature the hydro is we create a greater difference between the thermal expansion and internal stresses that the boiler see from temperature change. Another thing that has change is our willingness to accept risk of burns and other accidents. I remember stories about laying wet burlap to gain access to the firebox over hot brick to remove carbon cones from fire brick and burners. Also considered that if they did boiler washes in a shift that the firebox inspection could done on brick that had seen a fire within eight hours before the inspection was made and it would still have a level of heat in it

For Mr. Anderson, I feel for those burns. I lost a fight with GCR 18 wash hose and my right foot got a bath. Burns are not fun. A spitting air compressor has gotten me as well. I had a fireman trainee burn his arm lubing the front truck on 18 at the canyon when it found the cylinder saddle. The heat gun a couple of days latter said it was still 600 F an hour after getting to the canyon. It was easy to see why the burns could have happened with the perfect set of events happening..


Robby Peartree

In the two examples of this thread, neither report had any mention of pure material failure. The noted cause had nothing to do with material and for that matter, the material all tested to be sufficient for the use and design of the boiler. Had a material such as Stainless been involved, particularly when we consider the expansion and contraction and the possibility to work harden the material, making it more prone to failure, then we would have an issue. Keep in mind, boiler material from the day had plenty of copper and nickle in it making it more than ductile enough to handle a hydro test. Keep in mind also, there are many on this board who view a Hydro test as a very evasive test and one that should be reconsidered. Keep in mind, a steam test at 1.25 times MAWP was the norm for a newly manufactured locomotive prior to delivery. A much safer, better controlled and less evasive test!

Again, the issue at hand was not material composition or material failure. Though, it is true, the end result was failed structural integrity of the material.

"If you really want to impress an inspector......"

Hydro test with NO pump, hand pump, electric, pneumatic or otherwise. Doing one now, even as we speak!!!

JohnE.

"evasive test"?? Evading what? Could you please explain that?

Howard P.

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John,
You are missing the point of the original post. It is not a disagreement with the current code just an observation of differences of approach over time. When a material fails due to the environment it is subjected to it is still a failure no matter the cause.
Robby