THE GENESIS OF GASKETS: 37° Flared and 24° Flareless

Before starting SECO SEALS in 1969, Jim Scott Sr. worked as an:

• Aerospace Instructor;
• Aerospace Inspector;
• Aerospace Standards Engineer;
• and Aerospace Materials and Processes Engineer.

Founders Philosophy circa 1995

Jim Scott Sr. laid out his philosophy on the original website. This old version of our website can be found on the “Wayback Machine”.

37° Flared Fitting Gasket – SECO7 AS4824

The genesis of gaskets or “perception” of the need of a gasket began for Jim Sr. with an old 1926 Model “T” Ford he had while in college. In order to make that old 22 horsepower engine work, you had to have a head gasket and gaskets under the sparkplugs. Without the head gasket and the sparkplug gaskets you cannot contain the compression needed to fire the fuel-air mixture inside the cylinder. Also, without an electrical spark, the compressed fuel-air mixture will not explode. Having changed many sparkplugs on Model “T”s, Dodges, Plymouths, Chevy’s, Caddies, tractors, combines, B-24 and B-29 engines, etc., Jim Sr. soon learned that gaskets are essential to zeroing out the interface gap that occurs on all separable fitting assemblies.

F7U3 Navy Fighter – LTV (Ling-Temco-Vought)

Not understanding what compression yield is produces flawed expectations in separable fittings. Not paying attention to compression yield creates “busted knucks” and a pool of escaping fluid media. This phenomenon became acutely raised in a technical problem on the F7U3 Navy fighter built by LTV, Dallas. JP5 jet fuel in closed containers and properly transmitted is O.K., but letting that same JP5 loose in the stringers of an aircraft engine compartment will certainly produce a fire.

The F7U3 had some 1/2-inch fuel fittings that transmitted JP5 to the jet engine manifold. At LTV a jet engine caught fire on engine run-up and did a lot of damage. Needless to say, the pilot was no dummy and got out safely. The fire analysis found the genesis of the problem in the 1/2-inch flared fittings. “O.K. engineers, now fix it.” Since Jim Sr.’s job at LTV was to “ride herd” on the fittings, tubing and gaskets, he got the problem.

The solution is then, and it is now, to provide a soft malleable material (gasket) at the interface 37° flared cone. Being “perceptive”, Jim Sr. took some 25 (soft) aluminum tubing with .035 wall and flared it to the 37°. He made six of them and tried them in the assembly. “Bingo!” It worked like a charm. And it “buttoned up” the system 100 percent. In closing the loop, Jim Sr. established a CPC (company-LTV) standard with written torque and installation procedures. Flying the F7U3 was great, but only fixed one model series of the airplane. This did nothing for the national picture.

Convair / General Dynamics – B58 Bomber and Atlas Rocket

In 1958, Jim Sr. moved to California (the largest aerospace city in the world) to promote some of the lightweight fitting assemblies that were delivered for the B-58. (GDA – “Scott Connector Fitting System”).

While working for an aerospace manufacturer I called on GDA, San Diego. I contacted the Senior Design Engineer for the Atlas Rocket.

The senior design engineer had interest in the lightweight fittings, but his real problem was sealing helium gas. Two Atlas vehicles had been lost because of the loss of helium pressure in the Lox tanks. GDA was using gaseous helium to pressurize the Lox tanks. The senior design engineer said, “Jim, we have a very serious problem with our helium pressurization. We lost two vehicles and will probably lose more. If we don’t fix it, do you have any ideas?” “Bingo!!!”, the same problem we had at LTV, except this time it’s helium gas. Jim Sr. told the senior design engineer that “I can fix it.” Jim Sr. asked him what line size he was having the most trouble with. He said, “The 1/2-inch stainless fittings.” Jim Sr. advised him that it would take six to eight weeks to produce the parts.

Seven weeks later, Jim Sr. called again on the GDA senior design engineer with 50 pieces of the 1/2-inch (-8) gaskets. They went down to the GDA test lab and inserted them in the helium assembly. The gaskets were able to seal helium gas to a 10 to the minus 8 measured in a mass spectrometer. That pencils out to a one molecule a year leakage rate. You can’t get any better than that. “Bingo!”

The above efforts proliferated SECO’s standard into 22 line sizes in four materials (aluminum, copper, nickel and stainless).

24° Flareless Fitting Gaskets – AS4825

The 24° Flareless Fitting Gasket had its genesis in the MS 33514 design standard. Originally, the flareless fitting was a French design called the “Ermeto” sleeve. The original sleeve did not have a tail on it. The original “Ermeto” sleeve gave LTV’s tube assembly shop “fits” during the assembly process. If you take a look at the MS21921 sleeve, you will see that it now has a cylindrical tail. The design has two major flaws:

The first problem is in the sleeve biting into the tube. This sleeve bite produces a “stress riser” at the scarf cut periphery.

The second problem is in the fitting’s tube stop. In order to obtain “x” dimension, (center axis of 24 degrees included angle on MS33514 standard) sealing, the tube end should have at least .010 clearance. If this is not accomplished, the tube end can become the primary sealing periphery, “giving the installer a false sense of security.”

Some companies use machined profiled flareless tube stubs welded or brazed to the tube ends. This method of tube fitting is superior. Using the flareless gasket (AS4825) will also produce a 10 to the minus 8 leakage rate connection (one molecule a year). Flareless gaskets are available in aluminum (1100 series) and nickel (200 or 201 series). Torquing is the same as the hex-point turn method used on the 37° flared gasket.

Jim Sr.’s War Stories and Incidents

Over the years, Jim Sr. shared many war stories and incidents. Many of these he had first hand knowledge of while others were shared with him. Below are two of the incidents that he was personally involved with. They show his dedication to both his engineering discipline and his commitment to our military.

Bell Helicopter – Camp Pendleton

In the spring of 1990, I received a concerned call from the Bell Helicopter resident representative at Camp Pendleton, Oceanside, California. The conversation went roughly as follows: “Jim, we gotta problem on the Whiskey Cobra (AW-1) helicopter gun-ship used by the U.S. Marines. Can you come down here and give your gasket expertise to MAG 39 (Marine Helicopter AW-1 Squadron)?

I advised him, “Yes, when do you want to see me? How about tomorrow at 10:00a.m.? O.K., can you vouch for me at the main security gate? Yes, I’ll call down there now.” So I drove 65 miles down to Oceanside, went through their security, then to MAG39 headquarters. There I met the Bell representative who, in turn, introduced me to the colonel and his executive staff of MAG 39. The colonel then led me to a large conference set-up for the briefing of the squadron. Assembled there was a contingent of his pilots, maintenance mechanics, Q.C. manufacturing, purchasing and the Bell rep. The Colonel introduced me to his squadron and asked me to lecture them on the gaskets. Upon that introduction, I lectured the group on the merits of soft metal gasket technology. After that I gave a hands demonstration on how to install and torque the gaskets. This effort took about an hour. After the lecture, the Colonel dismissed them all, except his executive officer, two mechanics and the Bell rep.

The Colonel then asked me and his staff to follow him to an AW-1 (Cobra) parked out on the flight line. While we stood by the AW-1, the Colonel ordered the two mechanics to remove the access door under the main transmission. After the door was removed, we looked down under the stringers (ribs) where we observed a slurry of hydraulic oil, JP-5 (jet fuel), engine oil (mil-0 7200) and some foam. The Colonel said, in a very direct way, “Mr. Scott, see that (the slurry)!!! That is caused by systems leakage. It is inflammable, it upsets my pilots, it upsets me and it hinders our operations. My operational flight profiles look like a yo-yo (up and down, up and down). When that damned red light comes on, my pilots are obligated by S.O.P. (standard operating procedures) to land and to check out the problem. If we don’t do it, the pilot stands a good chance of locking up the servo valves, which will produce cavitation (no fluid). That’s bad.”

Then came the $64,000 question, “Can you fix it?”

For those of you who have never dealt with the U.S. Marines, you are in for a revelation. These guys are an organized bunch of professionals that mean business, and are extremely sensitive about things that can be injurious to their health. Having never met the Colonel before, I appreciated his directness. I looked him straight in the eyes and said, “Yes sir, I can and will fix it.” With that comment, I went over to the transmission and pointed out the blue colored “B” nuts (aluminum), and to the stainless steel “B” nuts (37-degree flared). Sir, I will give you all the gaskets needed to plumb the entire helicopter tomorrow, gratis. Further, I pointed to the dichromate colored “B” nuts (24-degree flareless fittings) with the comment, “Sir, I can supply all the gaskets for the aluminum 24-degree flareless assemblies tomorrow, gratis. For those stainless steel flareless fitting assemblies, I will give what I have on the shelf, but I will have to make some more of the Nickel-8 gaskets. This will take 8 weeks.

With that comment, the Colonel turned to his executive officer and said, “We’re going to do this!!!, so put it in motion.” We had lunch at a local beanery and I drove back to Seco, Costa Mesa.

The next day I delivered what I promised and demonstrated to the mechanics again on how to torque the gaskets without a torque wrench. Eight weeks later, I delivered the Nickel-8’s as promised. In the meantime, the Colonel asked for and received authorization to plumb (install) one complete Cobra for test. The gaskets “buttoned up” the leakage problem completely.

As an additional courtesy, the Colonel invited me to Pensacola, Florida, where I gave two lectures to selected personnel. He also directed me to go to the Army and Navy’s overhaul and maintenance facility in Corpus Christi, Texas, where I gave two lectures. Further, to the Bell Manufacturing Plant in Hurst, Texas, where I gave two more lectures.

This story does not end here . . . . .

Operation Desert Storm – January 1991

Did you ever get a phone call at 3:00 a.m.? Well, I did. What’s your first thought? “Has some of your family cashed it in?” This call came from the Bell representative in Saudi Arabia. After identifying him, I asked, “Are you drunk or in jail or both? Do you have any idea what time it is here?”(Jim)

“It’s 12 noon here. Get to work!!! (Rep)

“Well, what’s up?” (Jim)

“Jim, we have a serious problem here on seven of our Cobras. . . . .

They are leaking. . . . . It’s the 5th of January (1991) here and we are going into battle in about ten days. I have seven “ticked off” marine pilots here that are going to rearrange my anatomy if I don’t get them in this fight.”

“Well, what do you need?”

“I brought some of your (SECO) gaskets over here and our guys can’t fly because of no parts and leakage. . . . . Can you help me out?”

It mattered to me that those seven Marine pilots get into the fight . . . . . so I made up a ‘stash” of all the parts he would need, took them (the same day) to the supply officer at Camp Pendleton. The parts were on their way on a C5 to Desert Storm… It matters……