About Equivalence

We still get asked about tube equivalence. Sometimes the question is about a testing program with statistical parameters. At other times, it concerns listing as a supplier in ASTM D3241. Most often, the question concerns a non-existent "approval" that can somehow be had based on undefined terms and invisible, ever-moving, criteria. These questions all have the same false presumption; that somehow, our tubes are presumably (one way or another) unacceptable. While the questions are tiresome, our answer is always and forever the same: equivalence is undeniable scientific fact.

Precisely to ensure equivalent quality, ASTM International presents strict tube specifications and requires that tube users employ only tubes meeting specifications and which users, by themselves, determine to be equivalent. The specifications define, in technical terms, the “fitness for service” of inert aluminum tubes; important tube qualities that are incorporated into a Table in D3241 entitled “Critical Operating Characteristics of JFTOT Instruments.” If a tube property is determined to be meaningful, it gets added to the Table. Likewise, anything not in the Table is simply not essential, important, or of concern. (One example is the effort by some to promote confusion through inappropriate efforts to establish a particular vendor as, uniquely, “the” O.E.M. [Original Equipment Manufacturer]. That effort seems to constitute an unreasonable restraint of trade and a clear violation of ASTM Antitrust policy. It also contradicts a written Method Table 2 caveat clearly stating that a reference to Alcor, Inc. “is not an endorsement or certification by ASTM International.” However, make no mistake about this essential fact: We are the exclusive O.E.M. for our own very equivalent product).

Our inert tube reveals the full, rich, colors of fuel-related deposits which form on the surface. Although the determination of deposit colors is still the most critical aspect of a fuel determination or rating, the use of color is annoyingly subjective, indicating that the test itself is empirical or trial and error based. It has no scientific basis. It's the test that is quite subjective; not the tube. No inert tube can fix the fact of test results being subjective or amazingly variable.


Standard Heater Tube, Inc. has also completed and submitted equivalence results multiple times to ASTM Subcommittee J on Aviation Fuel. To view one example of a comprehensive Equivalency Study, please click here. Users are certainly free to consider this data. Aside from tube specifications and tube testing programs, knowledge is available that tube materials for various suppliers are derived from the exact same source. Once the mill supplies the specified alloy raw material, there’s no way for suppliers to alter essential and defined tube properties. In this way, tube equivalence is actually a built-in (guaranteed) feature of current tube supplies.


ASTM further, by policy, provides for product listing information to be incorporated into ASTM methods once new equipment has been "made available and shown to be equivalent." Unfortunately, ASTM hasn't provided a meaningful or technical definition for equivalence. In the face of the resulting confusion and the noted unfair resistance to free trade, we have adopted and produced the required “showing of equivalence” in a format that is simple, straightforward, and employs scientific logic. It follows common sense principles, too. To view this valid “showing of equivalence,” please click here.

Suppliers of quality heater tubes for D3241 employ varying technology to fix the final finish onto their heater tubes. Our methods are patent-protected and published. Others employ unpatented, unpublished, unrecognized processes. We conducted a Study of these various finishing methods and their effects, and presented the results to ASTM during a recent meeting of Subcommittee J. To view these results, please click here. Results, as expected for an inert product, showed equivalence among the various equipment suppliers regardless of the tube finishing method used.

Finally, Standard Heater Tubes are used in refinery and independent labs throughout the world; testing billions of gallons of jet fuel powering thousands of planes flying millions of miles around our planet. This fact is evidence that users have great confidence in the established equivalence of our product.

Tube equivalence is now undeniable. Equivalence is irrefutable and permanently true. Equivalence is even guaranteed. Plus, the proof of tube equivalence is actually straightforward, relying as it does on scientific evidence and the fundamental principles of general Chemistry. 


(How could it be otherwise, since the principles of Chemistry are fundamental, science based, and well understood? Contrast that with the trial and error JFTOT test, which is strictly empirical and involves practical correlations rather than scientific principles. The full name of the D3241 test itself actually tells us the test evaluates something about fuels that involves thermal considerations and fuel component oxidation, i.e. the Thermal Oxidative Stability of Jet Fuel. A moment's reflection will persuade even the most cynical observer that a test which is devised to indicate something about fuels simply cannot simultaneously indicate something about inert heater tubes. That idea just defies logic and doesn't pass the smell test).

For starters, there is the well-established principle from General Chemistry that the rate of a chemical reaction is known to double for every expected ten degree Celcius increase in the reaction temperature. If you compare this established concept to the notion within the ASTM Heater Tube Equivalence Protocol (RR-D02-1550) that equivalence can be demonstrated by a statistical plus or minus 5 degree Celcius difference from one tube to another, you're left with the astounding conclusion that two tubes whose performance varies by an entire 100% order of magnitude (namely, a ten degree Celcius temperature difference) are somehow considered to be and are even statistically defined as equivalent. The problem is that the trial and error test, being entirely empirical, isn't accurate to plus or minus five degrees. (Check the D3241 scope statement for verification).

The notion that an empirical or trial and error test can ever disprove a cold hard fact constitutes a colossal fools errand. The only thing being proven by such attempts is that people who cling to and promote that fallacy are, themselves, charlatans who mislead others on a grand scale through incredible, even unbelievable, falsehoods. Statistics can do many things, but statistics cannot alter reality. 

So, tube equivalence is more than simply obvious on its face. It is beyond being demonstrably true, even using the above un-official, statistical, plus-or-minus five Celcius degree criterion. Equivalence is axiomatic fact; validated through scientific inquiry. Equivalence is even guaranteed, by inclusion and adoption of alloy tube specifications in ASTM D3241.

Indisputably, the specified alloy used for making ordinary JFTOT tubes is comprised of 6061-T6 aluminum, and this plain fact has far-reaching consequences. For instance, aluminum alloy 6061 represents a material whose chemical composition is tightly controlled in a way that distinguishes its behavior from any other composition. Known as "aircraft aluminum," it is perfectly suited to aircraft applications. The uniquely specified material, once subsequently tempered to a regimented schedule called "T6" or "temper 6," fixes every chemical, mechanical, material, and physical property of the alloy permanently and irreversibly, creating an unalterable set of known features. The resulting material cannot be changed unless draconian measures (such as remelting the alloy at absurdly high temperatures) are invoked. Contrast that reality with foolish notion that tube differences can produce important effects in a weak trial and error empirical fuel test, and the presumed conclusion of non-equivalence becomes, well, unthinkable. It's because of this number one mandated characteristic within the tube specifications -- 6061-T6 -- that tube equivalence is actually guaranteed via specification. No serious investigator can believe otherwise.

Do you want to know why 6061-T6 alloy was selected for the JFTOT test? It's because that alloy, at conditions employed for the test, is already completely inert. For the doubters, try googling "Aluminum as oxidation catalyst." That search will result in a dearth of applicable entries, and that doesn't even reflect the rather mild conditions for JFTOT-related fuel-related deterioration reactions. The concept that one 6061-T6 tube is somehow measurably more "inert" than a comparably defined inert tube from another supplier is a concept that is beyond the pale.

Despite this reality, someone recently approached me to point out that a footnote to a Table in D3241 seemingly forbids use of any heater tube for jet fuel testing until such tube has been -- through testing -- "proven to be equivalent." They indicated that this requirement invalidates and disqualifies our tube from being used. That interpretation falls completely flat (even if we don't consider that at least five test programs have been successfully completed and submitted to ASTM for consideration). It is just mindless and nothing short of irrational to prioritize a Table footnote above the entire specification for heater tubes defining them as (1) being comprised of 6061-T6 Aluminum and also (2) 100.00% inert.

You'll even hear some people talking about this as if the real issue is that our product hasn't been "approved." That's simply disingenuous. For one thing, that approach attempts to move the discussion from something about technical features and technical capabilities to an entirely separate discussion about politics and about ASTM politics. For another thing, the notion of tube "approval" is only relevant to an examination of what is required for listing as a supplier in the ASTM Method D3241. The criteria for listing is actually set forth in the official ASTM booklet, Facts for Members. Documents and criteria there contradict the very notion of "approval." Those "Guidelines for Listing Suppliers of Alternative Equipment in ASTM Methods" set forth two concrete requirements, namely (1) that alternate equipment has been made available, and that (2) it has been shown to be equivalent. (There's nothing in the published Guidelines to establish how equivalence must be shown, or even to identify who needs to show it or by what authority ASTM can require anything at all in a voluntary test method. Nor, is there any basis to support withholding "approval"  or denial of a listing even after equivalence has been carefully and scientifically proven. It just makes good sense that a scientific proof of equivalence is sufficient).

This is to not even consider the fact that ASTM, by clear written policy, doesn't endorse or certify equipment suppliers to begin with. A statement of that reality is even included, specifically, in ASTM D3241. And, as a voluntary consensus organization, ASTM already recognizes that it holds no authority for vendor "approvals." Anything else is conflicted and instantly discredited. All users of ASTM Methods, as well as every supplier of equipment for ASTM Standard Methods, enjoys a measure of autonomy regarding ASTM. If that were somehow not possible, the concept of "voluntary consensus" would have no meaning whatsoever.  So, in sum, the twin notions of "Alternate Equipment Guidelines" and "Listing Guidelines" have become a smokescreen for efforts to politically blackball a particular vendor of inert and completely equivalent aluminum heater tubes for ASTM D3241. It's inescapably malevolent, too.

Aside from the irrefutable, permanent, scientifically demonstrated and guaranteed (by specification) proof of heater tube equivalence, and with no further regard for the separate issue that ASTM seemingly denies that it is already required by it's own policy and guidelines to provide an alternate supplier listing, there is a final and absurd obstacle laid down by ASTM Subcommittee J on Aviation Fuels. That obstacle is something called the Equivalence Testing Protocol. It has an official name as well: ASTM RR:D02-1550.

RR:D02-1550 is, in actuality, an official ASTM Research Report (notwithstanding that it reports no research and contains no data). However, even that shortcoming isn't a real issue with the Equivalence Testing Protocol. The two primary issues with it are (1) it is so obsolete as to be devoid of meaning, and (2) the erroneous approach taken within the Protocol is that heater tube equivalence, although undefined, can be statistically evaluated and demonstrated.

Recall that earlier we discussed the criterion of how a plus or minus 5 degree Celcius testing difference must reflect an entire order of magnitude difference in observed reaction rate. Thus, one tube that is known to be equivalent to another can reflect a reaction rate that is half, or even double, the reaction rate observed with another tube. That's definitely a testing problem. A larger and more intimidating testing problem is that equivalence is already guaranteed via the Specifications. Equivalence is a known fact, and known facts aren't subject to statistical evaluation. In other words, you can't use statistics to disprove something that is already axiomatically true.

RR:D02-1550 was adopted by ASTM in 2004. At that time, testing of jet fuels involved a visually-determined test result. Although that visual result is no longer definitive of jet fuel stability, it is still included as a requirement for the Equivalence Testing Protocol. In a word, RR:D02-1550 is obsolete. As a consequence, nobody in their right mind is going to deploy resources to complete a test program whose result isn't relevant or meaningful. Additionally, of course, ASTM "approval" isn't likely to be forthcoming on the basis of results from an obsolete test program. ASTM needs an ungraded Protocol; one which doesn't employ statistics in an effort to disprove equivalence, and one which provides a definition of tube equivalence that can actually be measured in some meaningful manner. Until/Unless that is done, RR:D02-1550 is nothing but an obsolete and meaningless obstacle placed in the pathway of a  legitimate equipment supplier.



In this section, I have shown how it is undeniable and beyond any reasonable doubt that tubes of various viable suppliers are equivalent. The basis for this fact is that the material composition and the alloy tempering schedule are both firmly established by tube specifications, which permanently, irreversibly, and unalterably fix every chemical, physical, mechanical, and material feature of these inert aluminum tubes. Consequently there is no technical basis for a belief that tubes could somehow be made "non-equivalent" through action -- accidental or even deliberate -- of an equipment producer.

Additionally, I have demonstrated that statistics are inapplicable as a means to "prove" tube equivalence. This is so because the JFTOT test is empirically or trial and error based. Lacking a scientific or technical basis, there is no reason to think that statistics could ever result in a valid technical result. Nor has any sensible theory been proposed, ever, by which non-equivalence can reasonably exist. Factually, multiple studies have recently emerged and have been presented to ASTM (including a "Ruggedness Study" of ASTM's own creation and completion). These, without exception, indicate that the range of variable results when testing fuels is closer to twenty degrees Celcius than to plus or minus five degrees. This result was obtained while employing only "ASTM-approved" tubes. Accordingly, such Study results have to be attributed only to already "approved" tubes; not ours. To ASTM, that's a mere inconvenient factlet.

A third conclusion about inert heater tubes (separate from any technical elements of factual tube equivalence or the inapplicability of statistics as a basis for "proof" of a known equivalence) is that ASTM's written "Committee Guidelines for Listing or Replacement of Test Equipment Suppliers in Standard Test Methods" actually requires that Equipment Suppliers be Listed in Standard Test Methods once such equipment has (1) been  made available and (2) shown to be equivalent. (It is an ASTM mystery how the very same folks who contend that a mere table footnote regarding "approved" suppliers takes precedence over the actual tube specifications for alloy type and metallurgy tempering schedule --- specs which guarantee equivalent performance in every respect --- can simultaneously ignore an equal table footnote making clear that ASTM doesn't endorse or certify any equipment suppliers. That's a selective interpretation and represents a confused outlook that really is incomprehensible. How can ASTM approve tube suppliers and also not endorse or certify them?) It is undeniable that both conditions have been met. (And, in addition, ASTM has an "Antitrust Policy" which prohibits exclusion of suppliers based on U.S. Antitrust Law -- the Sherman Act).

Notwithstanding these technical conclusions, there is a single political conclusion: There is no benefit to be had in contesting the unfairness or injustice being perpetuated against our company by a political ASTM subdivision. The existence of this political conclusion creates a natural tension against the three clear technical conclusions regarding (1) Equivalence, (2) Use of Statistics, and (3) requirements under ASTM Listing Guidelines and ASTM Antitrust Policy. That tension between politically-based forces and technical reality is one that only Subcommittee J, Committee D02, or ASTM International itself can resolve.


The only course for us is to maintain a steady focus on our rational customers and rational potential customers, while we and others wait for ASTM to display something approaching rational behavior. That is what we continue to do.

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Email: davidm@standardheatertube.com