The Latest At Valley Forge
Valley Forge is very proud to announce that our Load Indicating Fasteners have passed Military Shock Testing Standard MIL-S-901D!!
This is a rigid test that means great things for our fasteners moving forward with many different applications involving any degree of shock to the fastener while in service.
Shock Tests, Requirements for High-Impact Shipboard Machinery, Equipment and Systems
- Specification: Testing was completed per MIL-S-901D, Lightweight, Grade B, Class 1, Type C shock testing requirements.
- Location: Testing was done by Element Material Technology in Jupiter, Florida
- Purpose: The purpose of this testing is to verify the ability of shipboard equipment to withstand shock loadings which may be incurred during wartime service due to the effects of nuclear or conventional weapons.
- Load Indicating products tested:
- Standard SPC4™
- No-Standoff SPC4™
- Single Lever Maxbolt™
- Dual Lever Maxbolt™
- Mini Maxbolt™
- No-Standoff Maxbolt™
- MIL-S-901D is a common requirement for shipbuilders and other companies supporting the US Navy.
Our Maxbolt™ crosstalk video demonstrates the interactions which occur between fasteners in a typical flanged piping connection. This scenario is a perfect example of the complexity of many real-life bolted joints; particularly those with gaskets.
The demonstration clearly shows the limitations inherent with torque-tightening. The resulting differences between theory and reality can be significant. Not only does torque-tightening deliver limited accuracy in terms of resulting bolt tension, but it cannot tell you what happens once the torque wrench is removed.
All conventional tightening methods except for load indicating fasteners have this limitation, in that they are only useful for initial installation, and cannot be used to provide feedback from the bolts (and the joint) after tightening. It is true that methods such as torque-tightening, hydraulic tensioning, or turn of the nut techniques can be used in various ways after the initial bolt tightening in an effort to compensate for interactions such as bolt cross-talk. However these methods all fundamentally use the same approach; repeat the same (or a variant of the) procedure used during initial tightening. In the context of torque-tightening, a common practice in industry is to repeatedly torque the bolts in a joint over-and-over until the nuts do not turn. If the nuts turn this implies that the bolt became loose during prior tightening. Obviously this information is very subjective in nature and does not provide any useful information other than some form of load relaxation or joint interaction is actually taking place.
If load-indicating bolts are utilized, as in this video demonstration, the nature and magnitude of the interactions can be quantified, and more importantly corrected for. Rather than embarking on the time-consuming process of blindly re-torquing all bolts multiple times, a more calculated approach can then be taken which targets only those bolts with unacceptably low load.
Fastener Crosstalk is the phenomenon where as fasteners are tensioned, they affect the load on other fasteners around them, essentially speaking to each other.
We have been wanting to make a video that can show this intriguing display for a very long time. Because the Maxbolt™ can measure continuous tension in the fastener, there is simply nothing that can show crosstalk in fasteners better.
In making this video, an actual installation was done on an ASME class 300 flange unit. All measurements were recorded precisely during tightening with 3/4″ Maxbolt fasteners and a spiral wound gasket installed. The full procedure was: (1-5-3-7), (2-6-4-8) PCC- Legacy Modified.
First Pass: Fasteners were torqued to 55 ft lbs, which targeted 22% on the Maxbolt (40% of target torque STAR)
Second Pass: Fasteners were torqued to 138 ft lbs, which targeted 50% on the Maxbolt (100% of target torque STAR)
Third and Final Pass: Fasteners were torqued to 138 ft lbs, which targeted 50% on the Maxbolt (100% of target torque CW)
Calculated with K= 0.17, 100% on MB = 26,700 Lbf
During the first pass, there was a considerable amount of crosstalk in the bolts. A the very beginning all fasteners started hand tightened, but we found many were much more loose than this as we tried to torque them. During the second and final pass though, we really see the bolts crosstalking to each other and it reflected in their tension in the video. This video animation of an actual installation illustrates that controlling a joint with torque results in uneven tensioning of the fastener because of fastener crosstalk. With Maxbolts, designed preloads can be monitored continuously and show +/- 5% of targeted load to ASTM F2482 standards.
We hope you enjoy this video as much as we enjoyed making it. Please share and stay tuned for more animations like these to see more of the Fastener Revolution.
VF Technical Article by President, Ron Clarke
A bracket retrofitted to a rail-car axle. The assembly consisted of four bolted bracket mounts retrofitted to the axle and the bracket then fastened to the mounts. The whole assembly used a quantity of twelve 3/4” and 5/8” Maxbolt, load indicating fasteners.
Field tests were performed by OEM on the Maxbolt load indicating fasteners by gathering data from two brackets bolted onto a right and left, car axle. All twenty four Maxbolt load readings, against rail-car miles traveled during a nine week period.
After the first month and 1350 miles later, 9 out of 12 Maxbolts ~ 40% of the total fasteners, retained their initial preload of 75%
1 (one) Maxbolt: ~ 4% of the total, was down to 70% from initial 75% preload.
5 (five) Maxbolts: ~ 20% of the total, showed a load loss down to 65%
4 (four) Maxbolts: ~16% of the total, were down to a load of 60%
5 (five) Maxbolts: ~ 20% — were down to a low of 50%.
The fifteen bolts that had lost load were then all tightened back to 75%.
After the second month, and an additional 2557 miles later, 22 out of 24 Maxbolts ~ 92% of the total fasteners, showed no load loss with readings unchanged at 75%.
Only 2 (two) maxbolts: ~ 8%, were down slightly with readings of 70%.
At this stage the two bolts were tightened back to 75% and the car run for a further 2860 miles when another load check was conducted.
This check showed 23 out of 24 Maxbolts ~ 96%, holding load at 75%. With one bolt down at 50%.
Specifically with this OEM’s railroad bolting assemblies, safety is a first consideration. For this application, Valley Forge’s Load Indicator Technology not only assures this safety with an accurate and instantly readable assembly preload, but also ensures quick maintenance, with no further need for routine re-torquing, other than those individual bolts reading low on the Maxbolt dial. Load indicating bolts are not for all applications but their ability to read accurate bolt load at a glance or during tightening, makes it ideal for this critical bolted assembly. The quantitative clamp load readings displayed for this test, would have been by any other method, difficult and extremely expensive, if not impossible to obtain, without the Valley Forge Maxbolt™ Load Indicating System.
VFB Interview With Carlos Recart of Protorq – Chile
VFB: Tell us what Protorq does.
CARLOS: We have been dealing with bolted connection of all kinds since 1995, working with a wide variety of providers that offer different technologies. Thanks to that fact, and our experience today, we could conclude that what really matters on any critical bolted joint is bolts tension rather than torque. Thereby today we are able to support any kind of critical bolted joint in mining, power generation, petrochemicals and refineries, and whatever industry, just because we know that we must put all focus and attention in to the bolt tension.
CARLOS: Since 1995, so 20 years.
VFB: What are some of the interesting or unique things that you’ve gotten to see and do in your career?
CARLOS: Through the years we have seen and experienced many unique things, but I could say that all of them had something in common, that was to solve critical bolted joint problem. Let me tell a good one.
There was a mining company that contacted us because they were having cut bolts on a ball mill. In few words they stopped the mill every month to change 10 cut bolts, always at the same position. Besides the maintenance issue, stopping production every month means monetary costs. We end up showing the customer that they were just torqueing the bolts, and not considering any variables which affect the torque process. They were mostly not achieving the needed clamping load, which lead the bolts to getting cut because of fatigue. To solve the problem, and at the same time let them see what was wrong with their tightening procedure, we let them perform their torque procedure on SPC4 bolts. This showed them that the tension achieved on each bolt, just by relying on torque, wasn’t even close to the half of the needed clamping load. Then we finished the process by taking the SPC4 bolts to the right tension. This joint never failed again.
VFB: How did [you and] Protorq first get introduced to Valley Forge? How did the relationship start?
CARLOS: Well, it’s kind of a funny story.
In 2000, I was at the Expomin Mining Show in Santiago, Chile. Bret (Bret Halley, VFB’s CEO) was there to speak with a couple other representatives in liner bolts, etc. Long story short, I was asked to translate for Bret, and as he spoke to these representatives he didn’t seem to like them. While I was translating, I started to learn what they were doing and thought it was very interesting. I figured out that I should work with Valley Forge. And that’s how we came to start working together and began a long standing relationship with Valley Forge.
VFB: How have Valley Forge’s products been beneficial to you and Protorq’s work?
CARLOS: First of all, let me thank Ron and Bret for all they have taught us about bolted joints through these 15 years working together.
The Valley Forge “SPC4 technology” has allowed us to open doors. Innovative new technology and good level of knowledge will always open any doors on any market.
The SPC4 technology is by far the easiest way to solve any critical bolted joint issue. To have the answer for any kind of bolted joint, on any kind of industry at your fingertips, that’s everything. What else we could ask for?
VFB: How are the load indicating fasteners changing the work that you do at Protorq?
CARLOS: If you look inside any segment of the industry, that are working with and understand critical bolted join behavior, there’s one thing in common for all of them: they are all focusing on the bolt tension. It’s easy to see how the technology used on critical fastener has changed the last 20 years, more and more people understand that to have a safe and reliable bolted connection, all the attention should be on the bolt tension. So to working with load indicating fasteners, for Protorq, is to be ahead in bolting technology. To be number one in the bolting industry. To be the reference when people care about bolts tension. To be able to help and solve customer bolting problems. To protect our customers assets.
VFB: How is time saved with the use of load indicating fasteners as opposed to other methods?
CARLOS: With SPC4 technology all you have to do is to easily plug the probe to the bolt, tighten it till you read the desired tension, and save pushing just one button. Let’s say that you make a mistake with load indicators, for us to go there and double check that everything is right or wrong is so easy, repeat the mentioned process.
With UT, first you need to up load all the fastener specifications to the unit, then add all the factors like temperature and stress. Then identify every bolt, bolt groups, separating them by length and position, then create the same groups in the unit. Then read and save every bolt length before installation, then on tightening process, before any reading, you have to measure temperature and keep doing it all through the process as temperature variation affects the readings. To make the story short with UT you will need qualified people and much more time. Not to mention that if for any reason you lose the original measurements, you have to do it all over again.
VFB: What is the highest altitude mine location that you’ve ever installed our bolts?
CARLOS: That would be 4,400 meters at Mina Collahuasi in Chile. And then Las Bambas in Peru at 4,600 meters.
VFB: What is the most beneficial way to install larger fasteners?
CARLOS: Let’s say from four inches and up, the best way to do it is using tensioners, as you are turning the nut free of tension avoiding friction, because all the tension is on the tensioner. For smallest sizes on critical joint SPC4 is our choice.
VFB: What are the most common misconceptions with torque versus load in a bolted joint?
CARLOS: Just what you said [laughter]!
The easy way to understand why most of people have this misconceptions is this: In all industries you will find two kinds of connections; welded connections and bolted connections. If you want to apply for any outage or new project, you must follow the requirement specified on the basis. But it’s kind of funny that if you read the basis, it’s a must that all the welders have to be qualified and certified (have to be traceable) on each particular welding process. On the other side, the people that will work on bolted joint are not even mentioned on the basis. That’s way people understand very little about bolted joints, nobody really cares. Everybody says bolts are so easy “right is to tight and left is to loose”, “a correct torque wrench it’s enough”… But when they start to learn, then they are able to see that there’s a whole world of difference between torque and tension. I could say that after 20 years, we are still learning.
VFB Interview With Brad Webb of AC Sailing SF
“It all started when Bengt Blenduf, the well-known, international bolting Guru and educator was approached for his design recommendations by the Oracle/BMW racing team for their keel bolts. He thought it would be a great application for our load indicating technology, so he called me and directed me to their engineering. Valley Forge designed the hardware for the Maxbolt™ with the Oracle engineers, as you see it today.”
– Ron Clarke
VFB: How long you have been racing boats Brad?
BW: I started sailing when I was 12, in just a little dingy, in Wellington, NZ. I used to enjoy sailing on my own but for whatever reason, I enjoyed sailing with other people more and as I got further into it, I realized as much as I was quite a good driver, a Helmsman, I was a better crewmember, especially on the bow at the front of the boat. And then, my career happened more by accident then by good management. I decided to take a couple years off just to figure out what I wanted to do with my life: that was 20 years ago. I grew up looking at the big glossy magazines, with nice boats and sun drenched ports, and that seemed to me like a pretty good way to spend a couple of years. I wanted to go and sail the big blue water events, I wanted to sail on big fast boats, so I did. I had this drive to be better, I wanted to do things better every day I went out. I started sailing on the match racing circuits around the world, with some different skippers and my first America’s Cup was in 1995 in San Diego. Again it was more by accident than good management. Between 1995 and 2000, which was the next American’s Cup in New Zealand, I went sailing around the world, and sailed in a lot of different places. I think there was 140 events in 16 different countries over four and a half years. I did a lot of sailing, and sailed with a lot of people, in a lot of different situations and gained a lot of experience. When my second America’s Cup came around in 2000 with America True, the San Francisco team, I was pretty well prepared. Later that year I was picked up by Oracle Racing for the 2003 America’s cup, and I’ve been with Oracle Racing ever since, 5 campaigns and over 14 years.
BW: I sailed in the International America’s Cup Class (IACC) for four America’s Cups, from 1992 to 2007. That is what USA 76 is. The IACC, and the USA 76, was a great, great class, for 15 years, they built 100 boats. They are all sequential, so USA 76 is the 76th boat built. We were never successful winning the Cup in that class, but they were just a great boat to sail. We sailed with 17 people on those. Everyone had very, very specific roles, and the choreography that needed to happen on board to get the boat around the course, changing sails and sail it well, was quite detailed. If you got it right, you could have a great day out. And if you got it wrong, it was a bad day. The boats were very fast. We would sail around in those boats at 10 to 15 knots. Then we transitioned into the big T Hulls, and now we have transitioned into foiling catamarans, which are now sailing around at 45 knots. Quite a big jump in just a few years! But I bought USA 76 because I thought San Francisco needed some kind of connection to the America’s Cup. It’s a great boat, I know it well, and we put it together here in 2011, and we have been running it as a charter business out of Pier 39, coming up on 4 years now.
VFB: What distances did USA 76 race?
BW: We used to sail the IACC on a course that was effectively 12 miles, although you cover a lot more distance when you’re zigzagging up. Those races were about an hour to an hour and half long. We are now doing the same distance for the last America’s Cup in 2013, in San Francisco, doing the same distance in about 25 minutes in the catamarans. Still kind of doing the same distance but screaming around the race course.
VFB: What about the conditions of the race? What variation is there that the boats sail in?
BW: It really depends on the venue. The America’s Cup was held for a long, long time in Newport, Rhode Island, which was fairly benign. It would be 10-15 knots and fairly flat water, but quite consistent. When Australia won in 1983, they broke the longest winning streak in history and took the event down to Perth. The Regatta was held offshore there, and it was extremely windy with big waves. For those who watched, like me as a kid, it was extremely exciting because it was wet ‘n wild with thrills and spills. Then it was won again by the American’s and taken to San Diego which is inherently light, so the yachting there wasn’t all that exciting. New Zealand won it in 1995 and took it to New Zealand. That really showed what sort of range these boats can go through. We would have very light winds or very heavy, in fact in 2000 it was extremely windy. But again, you can have days that were light and then days that were wet ‘n wild and great TV viewing. They generally stop racing the boats at about 30 knots of true wind. For a couple of reasons, safety primarily, but after that, it’s tough to even watch and it’s even tougher for the race committee to set a fair course. At that point, it gets pretty extreme, boats are dragging anchors and it gets a little brutal. But that has generally been the range, from about 7 to 27 knots, so there is a significant amount of variation in the sailing conditions.
BW: For the IACC [USA 76 class] we used to do a lot of sailing, we would set up at a venue, or different venues around the world and do a lot of sailing. Once you had them together, they were an easy boat to put in the water and go sailing. The catamarans are logistically a little bit harder, because you have to put the wing and platform in everyday, and you have to use a crane. Just logistically they are a lot tougher. The cut boats we used to sail a lot, especially when we were based in Valencia. We sailed probably every other day for three years. That was a lot of sailing. Then, when we weren’t sailing, we were off sailing some other boats. So the USA 76 has been all over the world sailing far and wide; Auckland, Australia, all around Europe, lots of sailing in Europe, and both coasts of the USA.
VFB: How was USA 76 designed?
BW: It’s generally started using CSD analysis and making a hull shape, that is as fast as it can be built. And then the next part is engineering a structure that is as light, but as strong as it can be built. That then becomes part of the keel equation. But then you have to build everything else around it; the sails and the systems on board. Again, the lighter that you can make everything in the hull, and everything above the wood line, the more lead you could put in the bulb, because it was an overall weight that was part of the rule. Which basically makes the boat more powerful, which made the boat faster. If you could make the boat more powerful, it basically meant you were putting more lead in the bulb, but it then also meant that your keel, keel structure and all your fastenings needed to be engineered to take all that extra load. It’s a very complicated puzzle that needs to be just about perfect to work. There’s no room for error.
VFB: Where there bolting issues being encountered when you first came to Valley Forge for fasteners?
BW: There wasn’t necessarily a bolting issue, the Maxbolts where just the right product and application because you can see what the loading was. You can see that you were getting the numbers that the designers were asking for. We rely HEAVILY on analytics and engineering and design numbers, not only to build it, but to maintain it and monitor the boat, day in and day out. [When racing] we would take the keel on and off of this boat, probably once a month just to check it and make sure nothing was going wrong. For me it’s just all about reliability. Reliability was a HUGE thing for us when we were racing this boat because we had to finish races. We have to have faith in our gear. My mentality now is on a commercial operation, inspected by the coast guard, and I have paying passengers onboard. My liability is huge. Keels have fallen off and broken off America’s Cup boats in the past. Generally not because of the bolts, but for other reasons through fatigue and poor engineering. That still doesn’t mean that I want to risk sitting back and not doing anything. I have a lot of faith in how this keel was engineered. On these boats, the keel is just a huge, huge deal. If you engineered the hull and the rig and everything else light, there was more lead you could put downstairs. But it also meant the keel bolts were going to be working a lot harder, so the keel bolts were a huge part of the equation when these boats were being built, the way they’re engineered and the way the whole structure was engineered around the keel. Everything else doesn’t see that kind of load. I am quite close to the guy that designed the keel in the first place. We constantly talk about cycles and fatigue that the boat is going through. We took a lot of lead out of the bulb when we put it back in the water [commercially] and took some sailing rear off. So the bolts aren’t under what they were designed for, they aren’t seeing the design load they originally engineered for. It would be quite a lot lower. However, they are seeing a lot more cycles than they were originally engineered for. Which is why we haven’t had a lot of concern, because we think there have been some tradeoffs. Now that it’s been four years, we think the prudent thing is to take them out, check them, have them tested, put new ones in and see where we stand and ensure that we have confidence in the boat forward.
BW: The first set, they used to go in and out every month. That was when we were racing. Since I have bought the boat, and have a commercial license, we put a new set of bolts in the boat in 2011 and haven’t touched them since. We originally put them up to about 80% of their max loading, which we were happy with, and they haven’t moved. We have made sure that we have kept them nice and greased because they are in a pretty harsh environment, so we try to look after them as best we can. Now we are taking them out and putting a brand new set in. We are going to send them back to Valley Forge for testing and that will give us an accurate picture of life and the environment that these bolts have been in. What we are going to learn when the new bolts come and we swap them out, is if there has been any fatigue on them, or excessive amounts of corrosion, just what’s going on. For a number of things, but mainly we can learn what kind of long term environment they can go into. For us, it gives us an idea of where we are in the cycle of these bolts. When we put these brand new ones in and send the other back and we find that they are absolutely pristine, then we know the least amount of time we can get out of them, without any concerns.
Post interview update: The USA 76 was taken out of the water on March 18th at the KKMI Marine Facility in Port Richmond, a first class boat yard in San Francisco and AC Sailing’s first choice for haul out and maintenance needs. They removed the in service Maxbolts™, and installed the brand new set. The photos show her out of the water with her 14 foot long keel and 40,000 pounds of lead attached at the bottom. You can see the installation using the VF hydraulic wrench and the new bolts in position and tensioned. The bolts were fully lubricated, then painted with an epoxy protective coating after install.