Buckleys are proud to sponsor Peter Woodsford, who in his spare time delivers essential packages for the Emergency Rider Volunteer Service. www.servkent.org

This invaluable service assists our NHS (National Health Service) with urgent blood and organ deliveries to hospitals around the Kent and London border.

Peter has been required to supply his own bike, which has been painted in the liveried colours of the service.
Peter then has to fund the running of his bike himself.

A2 SGS Spark Gap Setter

For setting the output voltage of Spark Testers i.e ST-AC 100, C200K Mk5 and PPM Mk3. Not recommended for use with TMF Spark Testers..

A4 Adaptor

Used to connect straight Phosphor Bronze Electrodes (E104 – E124) or straight Silicone Rubber Electrodes (E204 – E224) direct to test probe handle.

Insulated Extension Rods

- A7 220mm long
- A8 330mm long
- A11 460mm long
- A9 1000mm long

A12 Shoe Attachment

Connects Rolling Springs Electrodes (E704 – E748) to an extension rod, and can also be used to connect straight Phosphor Bronze (E104 – E124) or straight Silicone Rubber Electrodes (E204 – E224). Only suitable for DC equipment.

A13 Earthing Magnet

For making an Earth connection on smooth surfaces..

Other accessories are available including carrying cases, earth leads and test probe handles.

These courses are designed to:

Inform participants of all aspects of high voltage testing with Holiday Detector equipment.
Give participants an insight into the theory of high voltage testing.
Offer practical advice on the problems that are encountered in real life testing situations.
Training sessions are normally based at our factory in Kent but we are usually able to arrange on-site training at any location in the UK.

For further details on Buckleys Training Services, please do not hesitate to Contact Us.

We offer a fast turnaround service to UK customers to assist in keeping down time to a minimum. Estimates will be given before any repairs are carried out.

If you are a non-UK customer, please contact our sales department who will be able to advise you about the location of your nearest repair facility.

For further details on Buckleys Repair Services, please do not hesitate to Contact Us.

If you are a UK customer, we will also provide you with a useful reminder when re-calibration of your equipment is due. Non-UK customers should contact our sales team, who will be able to advise them of the location of the nearest calibration company.

For further details on Buckleys Calibration Services, please do not hesitate to Contact Us.

To help G & S Roofing test the integrity of a 20,000 sq metre roof at Arsenal Football Club’s state of the art Emirates Stadium in north London.

To test the roof material (constructed from decking plywood and Sarnafil membrane), quickly, cost-effectively and accurately, despite the challenge posed by the many steel roof penetrations.

The Solution

Rather than employ a sub-contractor to test the roof (as had been its previous practice) G & S Roofing used Buckleys’ award-winning Roof Testing Kit to check for defects by passing a high voltage over the surface.

Key Benefits

G & S Roofing was able to prove that the membrane was watertight on handover day.

The company is now equipped with a robust, reliable, easy to use DIY kit that eliminates the need to employ costly sub-contractors.

To combat Accelerated Low Water Corrosion (ALWC) on steel structures by measuring the effectiveness of the cathodic protection system.

To find a quick and easy method of monitoring the efficiency of the sacrificial anodes that could be carried out on a regular basis without specialist skills.

To reduce the need for costly diver surveys and survey launches, that also impact on port traffic and result in pier closures.

The Solution

Buckleys’ Marine Survey Kit was tailored to Dover Harbour’s individual requirements, using silver/silver chloride /sea water reference electrodes to check the corrosion status of the harbour wall piles.

Dover engineers installed a series of measuring points, every few metres, along the sides of the piers, to which the Buckleys’ system can be connected and a reading taken in seconds.

Key Benefits

Dover Harbour has established a cost-effective, efficient and rapid method of checking the effectiveness of the protective anodes.

The port can carry out inspections on a far more regular basis at less cost and with little disruption to port operations.

A pier can be surveyed by two engineers in two hours, compared with two days for the earlier thickness measurements.

Do I have to change the Test Voltage when the substrate is concrete as opposed to steel?
No, the concrete only connects the Test Voltage to one side of the material, it is not being tested. If the concrete is dry the sensitivity of the Holiday Detector may need to be increased to compensate.

How small a hole can I find using a Holiday Detector?
If air can pass through the hole the Holiday Detector can find it.

When I re-test a membrane applied to concrete I find other faults that did not show up on the first test, why is this?
These are thin areas where the Test Voltage was equal to the Dielectric Strength of the material. The first test was enough to weaken the material in the thin area but not enough to make a fault. The second test was enough to break down the material.

Can I test coatings that are damp because of dew etc?
No, dampness makes the surface conductive and any test with a Holiday Detector becomes ineffective. All surfaces must be clean and dry.

I test the insides of tanks and every time I touch the metal case of the Holiday Detector I receive a shock, why is this?
This is because you are working in close proximity to the high voltage which is charging you up. In your case this is more noticeable because you are standing on an insulator, which is stopping this charge leaking to earth, also the surface has been charged to the test voltage. All that can be done is to wear insulating gloves and avoid touching earthed metal. It is more noticeable in dry conditions.

When testing a surface and moving the electrode, sometimes the alarm sounds for no apparent reason, as no fault can be found – why?
As the electrode moves over the surface it charges it to the test voltage, taking current from the Holiday Detector which activates its alarm. The charge current is proportional to the area of the electrode on the surface, also if the surface is damp this will have the effect of increasing the area needing to be charged. The answer is to adjust the sensitivity of the Holiday Detector but if this is not possible make sure that the surface is clean and dry. The only other option is to reduce the area of the test electrode.

The hand-held unit measures the electrochemical potential of the structure under investigation against its own internal silver/silver chloride/sea water reference electrode. The potential is then displayed on the Bathycorrometer^® multimeter. This potential may be noted by the diver at the time the inspection is carried out or can be transmitted to the surface by the use of a Surface Display Unit.

The Bathycorrometer^® allows a diver/inspection engineer to select a given location, on an immersed structure, at which the structure to sea water potential is to be measured. The electrochemical potential of the structure under investigation at this location can be determined to a high degree of accuracy (+/- 5mV ).

The measured potential will enable an assessment of the level of cathodic protection on the structure under investigation to be obtained. If the potential is less than 800 mV vs an Ag/AgCl reference electrode in aerobic conditions, then insufficient levels of cathodic protection are being achieved. If the potential is in excess of 1100 mV vs an Ag/AgCl electrode then excess levels of cathodic protection are being applied and there is a danger of cathodic disbondment, detachment of the structure coating. Indeed, in the case of high tensile steels, a high negative potential may cause hydrogen embrittlement.
underwater diver

The potential readings provided by the Bathycorrometer^® will provide the structure’s operator with information on the efficacy of the installed cathodic protection system and locations of any areas where only partial levels of cathodic protection are being achieved. If there is a likelihood of corrosion the electrochemical performance of sacrificial anodes can be checked to determine if there are any areas of over protection. In the case of impressed current cathodic protections there is the possibility of coating damage due to over protection. This can be detected using the Bathycorrometer® and suitable measures for mitigating against excess levels of cathodic protection can then be taken.

Measurement of the structure to sea water potential with a portable silver/silver chloride electrode from the surface will provide information on the mixed potential of the structure over a large area. However, there may be areas of low protection on a given structure that will not be detected using a portable half cell. The information from portable half cells can sometimes be misleading and will in all instances require an electrical connection onto the structure under investigation.

The Bathycorrometer^® enables measurements of the structure potential at a precise location and can provide a considerably more accurate assessment of the levels of cathodic protection, the spread of the cathodic protection current and likelihood of corrosion than other inspection tools. This is particularly important in the case of cathodic protection systems for offshore structures, where the levels of cathodic protection at critical locations (e.g. nodes) can be accurately determined. The data provided by the Bathycorrometer^® will enable the structure’s operator to ensure the structural integrity of the structure under investigation, satisfy the certifying authority that the structure has an adequate level of protection against corrosion and ensure the structure design life can be achieved.

The Bathycorrometer^® can be used to check the performance of cathodic protection systems on a wide range of structures, from offshore platforms, buried pipelines, sub sea modules, ships and jetties. It is particularly useful for measurement of the structure to sea water potential in instances where it is not possible to make electrical contact with the structure under investigation using any other technique.

The Bathycorrometer^® can be provided with K series electrodes for calibration purposes to check the accuracy of the internal electrode each time a dive is conducted and a set of potential readings are taken. This will assist in providing a high level of confidence in the results being obtained.

In brackish waters the Bathycorrometer^® can be provided with a gelled silver/silver chloride/sea water electrode. This electrode will provide a known electrochemical potential that will not vary with chloride concentration in the water. Thus the inspection engineer has no need to adjust the potential readings obtained to compensate for variations in water salinity.

The Bathycorrometer^® can be provided with a Surface Display Unit (SDU) as an optional extra . The measured structure to sea water potential is then transmitted from the Bathycorrometer^® to the surface by a 4 to 20mA signal. The surface display unit then converts this signal to a direct voltage read out, for interpretation by a corrosion engineer on board the survey vessel.

It is important to note that divers using the Bathycorrometer^® and working in the vicinity of impressed current cathodic protection systems must follow national and local guidelines for the safe use of electricity under water.

The Bathycorrometer^® has gained international acceptance as a diver–operated inspection device, has a proven track record, and is used throughout the world.

Note: Bathycorrometer^® is a registered trade mark and is manufactured by Buckleys (UVRAL) Ltd.

It is normally expressed in Volts/mm. The material manufacturer should be able to supply this information but if not an approximate value can be found using a Holiday Detector.

Calculating the Dielectric Strength

1. Obtain a sample of material with a uniform thickness of about 1mm applied to a sheet of metal.
2. Connect the Holiday Detector to the sample with the earth lead connected to the metal and the high voltage probe (via a pointed probe) to the surface of the material.
3. Starting with the output voltage set to minimum, slowly increase the volts until the material breaks down and the alarm on the Holiday Detector sounds.
4. Lift the HV electrode off the surface of the material and note the output voltage.
5. Repeat this test a number of times on a new area of the sample at least 20mm from where any previous breakdowns have occurred, noting the breakdown voltage each time.
6. Take an average of the voltages and then 75% of that is approximately the dielectric strength of the material.

So now you have a value for the dielectric strength we can look at how this relates to the test voltage calculated previously.

It is important to check, before you start testing, that the test voltage you have selected is not so high that it will actually create faults in a coating. This would rather defeat the object of holiday detection. To demonstrate this let’s look at a worked example.

Example

Say we have a coating 2mm thick which has a dielectric strength of 8400 V/mm. Using the NACE formula the test voltage is:

We know the dielectric strength is 8400 V /mm so for 2mm the maximum voltage before breakdown occurs is 2 x 8400 = 16,800 V. In this example then the test voltage of 11,180 V can be used since it is less than the breakdown voltage of the material (16,800V).

So what if the dielectric strength is below the calculated test voltage. Let’s look at the same example as was shown above, a coating 2mm thick but this time it has a dielectric strength of 5000 V /mm. Again the test voltage is calculated to be 11,180 V but now the breakdown voltage of the material is 10,000 Volts (2 x 5000). This is clearly less than our test voltage and attempting to use 11,180V to test this coating would result in the creation of more holes.

In this instance high voltage holiday detection may still be used to locate flaws in the coating, but some further testing is required to ensure that this method is valid.

Referring to the example above of a 2mm coating with a dielectric strength of 5000 V / mm, the validation test would be as follows:

1. Make a small hole in a test piece.
2. With the electrode over the hole slowly increase the voltage until the spark jumps the gap. Note the voltage (which in this instance, on a 2mm coating, would be ~ 5000 V).
3. To determine the test voltage, use a value midway between the test voltage calculated using the NACE formula (in this case 11,180 V) and the minimum voltage determined from the above test (~5000V). This works out to be 8090 V. ((11,180 – 5000) / 2) +5000).
4. Now make some more holes in the test piece (making sure there is more than 20mm between each hole), this time at angles, and using your test voltage (in our example 8090V) ensure that it is possible to locate the faults.

This method of finding the test voltage is fine if all you are looking for is cracks in the coating (that is complete faults that go all the way through the coating to the substrate). Indeed, many standards only require this type of fault to be detected. However, with careful selection of the test voltage, it is possible to find a variety of different flaws. See A guide to using DC Holiday detectors for more information.