Anyone with some experience in servicing scuba equipment will have encountered one of the following situations: 1/ seized parts (damn, I can get the bugger loose), 2/ technician induced damaged parts (damn, I just damaged the customers’ equipment) and 3/ broken or damaged tools (damn, why did that tool just snap).
If you haven’t encountered any of those situations, don’t worry, it’s a guarantee, it will happen to you one day. This article will go over some reasons for this to happen, how you can avoid and get yourself out of those prickly situations. In other words, avoid being part of the elite cult: ‘a bad workman always blames his tools’.
Once in a while you will come across components which present the technician with a challenge in order for them to be removed. Despite even using a little excessive force, the part simply won’t budge. Reasons for this to happen:
- Parts have been over tightened upon assembly.
- Parts have corroded holding the assembly in a tight grip.
- The part was cross threaded during installation and possibly broken parts of thread lock the part in place.
- Combinations of the above.
RELEASING SEIZED PARTS:
If you encounter seized parts and it feels that you are about to use much more force than normally would be required, it’s time to put down the tools and consider your options before irreversible damage occurs.
Commonly used methods for releasing seized parts fall under one of those categories: heat, mechanical and chemical application.
Mechanical: the use of extra force could be required but too much force is likely to damage the components. The method of ‘a thousand-taps’ is sometimes all it takes to get the parts moving. Example of this method: with a spanner over the seized component, gently tap-tap- tap the end of the spanner with a hammer to ‘shock’ the component loose (gently is the keyword here). The use of the ultrasonic cleaner can be considered as falling into this category.
Heat: the use of the ‘blue torch’ a.k.a. an oxy-acetylene or butane torch is not appropriate given the fact that many inner components are O-rings or might be made out of plastic materials.
Chemical: the use of chemicals could be used to dissolve the corrosion, however those chemicals cannot be so strong or be applied for such a long time that they actually dissolve the parts or eat away the chroming. In our opinion the use of penetrant oils and similar products is not appropriate for breathing air applications.
Our favorite technique is a fine balance of the above mentioned methods. When we encounter items which are really stuck, prior to last ditch attempts and overzealous use of force, we will soak the parts in an ultrasonic cleaner with hot soapy water for 5 to 10 minutes, then try to loosen the part once more. If this fails we would repeat this procedure a few times and maybe give it one last attempt in an ultrasonic cleaner with an appropriate acid solution for a few minutes. If this technique fails you, all what is left is really going after it, in which case parts or tools might break.
Sadly enough, in stubborn cases and despite all of your best effort and attempts, at some point, damage to the part will occur resulting in the part(s) having to be scrapped or replaced. Don’t feel bad about it, not all life can be saved (especially not when it’s been taken poorly care off).
DAMAGED PARTS CAUSED BY THE TECHNICIAN’S COMPETENCE:
There’s no excuse for a technician damaging components due to poor judgment. Taking pride in your job and choosing the correct tool for the job will prevent this from happening in 99.9% of the cases.
Some of the common cause’s technicians damage components:
- Use of imperial spanners, sockets or hex keys on metric sized components or vice versa.
- Use of Pozi drive screwdrivers on Philips head screws and vice versa.
- Use of slotted screwdrivers whereas the slotted screwdriver is undersized for the slot.
- Over tightening components.
- Tools slipping over components.
- Dropping components.
- Holding components directly in hard steel vise jaws.
- Using of adjustable spanners, pipe wrenches or pliers with teethed grooves (those teeth are likely to leave a nice footprint).
- Not engaging/inserting hex keys at full depth into their machined sockets in the component. If the hex key is not fully inserted, the chances for it to slip and damage the component are significantly increased.
Face it and live up to you mistakes, damaged components should be replaced. If it’s your own equipment, maybe, a little scratch isn’t the end of the world, but on customer’s equipment, we feel this is a no-go situation and technicians’ induced damage should be repaired at the technicians’ expense even if the damage would not be visible on the outside of the equipment.
Just as for damaging parts, tools can be as easily damaged if an inappropriate tool is used for a specific task or the tool is misused (read abused). Some examples:
- The use of the tool beyond their rated application: if a socket is rated for a torque of 30 Nm and you apply 120 Nm (i.e. 4 times its rated maximum torque), likely something is going to give away. This one really applies to thin walled sockets used to install and remove yoke nuts.
- If extensions are used over spanners or other tools in order to create a greater leverage, there’s always a chance the tool might bend or snap.
- Using pin spanners with pins that are significantly smaller than the connecting holes in the component the spanner is used upon. If you apply the force too far out and downward, there is a change the pin spanner might slip, resulting in bent or broken pins and possibly damaged components.
SOME TIPS AND TRICKS:
- Do not over tighten components and use a torque wrench where recommended by the manufacturer. Torque specifications are not just there to make sure the components is ‘tight’ but more often than not just to prevent over tightening and damaging components.
- It could be beneficial to add a little dab of manufacturer’s recommended grease on metal to metal threads. However, technicians should be made aware that lubrication of threads—and a whole host of other factors—can cause fluctuation in torque readings. Hence not all manufacturers recommend this practice (e.g. Apeks).
- Choose tools so you’re able to apply the force as directly and perpendicular as possible to the components. This could be of great importance when using tools that have pins. If forces are applied unilaterally (to one side only), there is a big chance of the tool becoming detached off the part, resulting in shearing the pin off during the rotational motion of the tool and mar the component. So if possible at all, keep pressure on the tool in line with the components axis.
- For hook, c-spanners and pin spanners, keep you tool in a parallel plane to the top of the component.
- For hook and c-spanners choose the tool so it gives the best possible fit to the component, i.o.w. have the diameter of the tool be as close as possible to the diameter of the component.
- If a nut or a screw seems impossible to remove, you might want to consider the fact that there is a possibly that this nut or screw has a left-handed thread (a quick check in the service manual will be sufficient to confirm or disapprove this). An example of this is the shutter valve of the Aqualung yoke ACD version.
- If you’re trying to remove a cylinder valve and the valve seems to be extremely tight and requires a lot of force to move or doesn’t move at all, well… you might want to double check if the cylinder is empty and no longer has any pressure inside.
- DIN inserts for cylinder valves often get stuck because of 2 reasons: corrosion and a rounded inside hex (the rounded hex is most likely caused by the use of the wrong hex key to install or remove the insert). Being stuck because of corrosion can be eliminated by removing the insert on regular intervals and cleaning the insert (let’s say 2 weekly) or only installing / using the insert when required. If they get stuck and the hex is damaged… a fair attempt can be made by using square stud extractor or a screw extractor and scrapping the part. Do yourself (and possibly as well the next in line professional) a favor, do not try attempting drilling it out free-handed.
- A stuck DIN hand wheel retainer/connector can be a real pain, especially if the inner hex is damaged. This part could become stuck because of corrosion and/or over tightening. The stuck component would require additional force to be applied resulting in the hex to become rounded or the part to break. If the retainer cannot be removed from the body, you will not be able to properly service the first stage and basically it’s a write off. There are commercially special tools available on the market to deal with this specific issue. Alternatively, you might have to resort to stud extractors and scrap the part.
- Eternal hexagonal shaped components (e.g. a bonnet nut of a cylinder valve) that are stuck and have the corners rounded, can be removed by using extractor sockets and scrapping the part.
- Corrosion of parts, salt accumulation… can greatly be avoided by properly rinsing the equipment after use. Many manufacturers have very specific guidelines for this. It might be worthwhile reading up on those in the user manuals and educating your customers.
Nothing contained in these notes or shall be construed to over-ride or replace the relevant standards or manufacturer’s recommendations, manuals, data or product specific training. The contents are believed to be correct to the best of our knowledge and are offered in good faith. No warranty is expressed or implied. The author, Scuba Clinic Co., Ltd. accept no liability for any loss, damage or injury however caused resulting from information contained in these notes. It is the responsibility of the reader to verify the correct information, practices and procedures prior to commencing work.