Question 1

How long have you been providing such testing services?

Peter Plewa · Accepted Answer

We began providing ultrasonic testing services for pipe and tanks in 1994.  Prior to that time, we were involved in the field of chemical water treatment, which provided a first hand understanding  to most corrosion related problems, as well as realization to its significant limitations.  The Principal and President of CorrView, William Duncan, began his career after Graduate School as a research scientist and inventor for a major multi-national think tank.

Question 2

To what areas of the United States do you provide your services?

Peter Plewa · Accepted Answer

We travel throughout the United States on a regular basis. Frequent cities are Chicago, Washington, DC, Boston, Dallas, and San Francisco. Furthermost investigations have been to Alaska, Guam, and Australia's Northern Territory. We recently completed our 1,050th building property investigation. Our latest Business Resume provides some idea of our involvement in this field

Question 3

What is the accuracy of ultrasonic testing?

Peter Plewa · Accepted Answer

The high quality Olympus Ultrasonic Thickness Gauges we employ have an accuracy of near 0.001 in., which is greatly dependent upon the equipment employed and operator experience.  Most errors in measurement, on the other hand, often relate to low cost equipment and/or an inexperienced operator.  Performed properly, a wall thickness measurement using ultrasound is equally accurate to a quality dial caliper.  Calibration to standards representative of the material being examined is required initially when setting up and then periodically during the inspection process.  Materials such as carbon steel, galvanized steel, brass, stainless steel, and copper are the most common subjects and are relatively easy to test.

Cast iron and ductile iron, due to their rough internal and external surface textures, grain structure, and due to their natural porosity of the metal, absorb more of the sound signal to make measurement far more difficult.  In addition, sound velocity through such metals can vary from section to section, making measurement far less accurate by up to 20%.  Concrete and transite pipe cannot be tested ultrasonically.

Question 4

Can testing be performed on a piping system while operating as normal?

Peter Plewa · Accepted Answer

Yes.  Testing is totally nondestructive as well as non-intrusive, and will not impact building operations in any way.  The system does not need to be shut down nor does the pipe need to be drained.

Question 5

Can you test pipe and tanks that have been painted?

Peter Plewa · Accepted Answer

Generally yes, although it depends greatly upon the type of coating, and if whether multiple coats of paint have bonded strongly enough to each other to transmit sound. Since any paint or coating is of far less density than any metal, the movement of sound through it slows dramatically to trick the instrument into interpreting a longer length of travel through a much thicker pipe or tank wall. The results is a falsely heavier wall thickness measurement exceeding the true thickness of the subject metal and paint itself. In order to eliminate the need to scrape away the paint or coating, as well as potentially damage the pipe itself, we employ a feature of our Olympus instrumentation called “echo-to-echo," which essentially negates the coating thickness. This method may not be possible for heavier and especially rubberized coatings, or for very old pipe or metal surfaces where the paint is cracking and peeling. An alternate method is to physically remove the coating in the areas tested which not only requires significantly greater effort, but also adds later work to the maintenance staff in re-painting the pipe. A common shortcut to measure the thickness of the paint coating and deduct this value from all readings made across both paint and metal introduces potentially significant error into the investigation since paints and most coatings are applied unequally.

Question 6

Can you take wall thickness measurements through insulation?

Peter Plewa · Accepted Answer

No. Ultrasound requires direct contact with the pipe itself.  Typically, the removal of a 9-12 in. width of insulation is sufficient.  For larger piping systems, removing only the bottom half or less may be required, rather than the entire circumference - especially where a specific area of interest exists.

Metal jacketed insulation adds difficulty to any investigation, and should be removed in advance.  Asbestos insulation must be properly abated in the areas specified for testing.  Pipe having a heavy outer plastic or vinyl jacket must have that jacket removed in the areas tested.  For many investigations, the removal and replacement of the insulation presents a significant impediment and additional cost.

Question 7

Does CorrView Remove and Replace Insulation?

Mark Duncan · Accepted Answer

The majority of our investigations involve piping systems which are insulated, and therefore we require its removal at locations where testing is to be performed. Typically we require the removal of a 9 - 12 in. section.  Procedurally, the insulation is sliced open and moved to the side, ultrasonic testing is performed, and the same section if insulation is then replaced and the cut seams taped.

While our technicians can remove standard fiberglass insulation at each test location if necessary, we are not insulators and will not be able to replace it or make repairs.  Where the insulation is wet, deteriorated, or damaged, replacing the same insulation may be impossible, and we will not have exactly that size and thickness on hand.  Any roof level insulation will be protected by an outer vinyl or aluminum jack which requires special tools and effort to remove and replace - preventing our testing unless removed in advance.

Most importantly, any effort our technicians spend on insulation removal will take away time which was designated for testing and may inevitably reduce the number of test locations we are able to address.  In order to not impede the testing progress strongly suggest allocating building engineering staff or an independent insulation contractor to remove and replace sections insulation.  This benefits the building by allowing us to gain more information ultrasonic thickness data, examine more pipe, and restores the opened areas of insulation to their original condition.

Question 8

Is ultrasonic testing possible at hot pipe, such as high temperature hot water and steam lines?

Peter Plewa · Accepted Answer

Yes, but special procedures must be followed. High pressure steam lines at near 425 °F will slow any investigation considerably. Pressurized high temperature hot water presents a similar issue. First is the need to remove up to 6 in. thick and potentially hard formed insulation, followed by working in close physical proximity to such hot surfaces and the need to actually touch the pipe with the surface probe. Metal expands beyond its normal wall thickness at higher temperatures - therefore requiring an additional effort to perform calibration of the equipment to standards at the same temperature. High temperatures will destroy the sensitive and fragile ultrasonic transducers. Therefore, they must be allowed to cool at intervals, which in turn slows any investigation. Overall, additional time should be planned for any high temperature investigation. Lower temperature piping systems such as hot water, reheat, and domestic hot water present far fewer issues of concern.

Question 9

Can you test underground piping?

Peter Plewa · Accepted Answer

No. Ultrasonic testing requires direct contact with the pipe requiring excavation. While alternatives exist in the form of ultrasonic "pigs" that travel inside the pipe, many issues exist including a high cost. Additionally, guided wave can be used to inspect underground pipe, however the length of scanning ability can be greatly reduced by pipe and ground conditions. There is an alternative called "pigging," which sends a large device through the pipe itself and is the only option for riser piping behind walls or underground pipe. Limitation exists relative to pipe size, and substantial preparations are required, including the temporary removal of the piping system from service. Clean pipe benefits its accuracy, and for that reason a high pressure cleaning prior to testing is often advised - itself a time consuming process. We can provide further information on pigging and guided wave upon request.

Question 10

How long does it take to perform ultrasonic testing?

Peter Plewa · Accepted Answer

Investigative time is directly related to the physical accessibility and location of the pipe, building size, external conditions, material, insulation, high operating temperatures above 200 °F, specific security or safety delays and whether testing is localized to one area of the property or spread throughout multiple areas or properties. Investigating a dry fire room having 4 zone valves would require far less time than a single high pressure steam line traveling within an underground steam tunnel system across multiple campus properties. Centralized HVAC systems generally require less investigation than packaged heat pump units having varying conditions and different piping sizes and layouts. Galvanized steel pipe, due to the very random nature of its deterioration, often requires additional scanning to identify its characteristic random localized deep pitting. Generally, we can address approximately 40-50 individual examples of pipe within a full day of field testing, and often more. Where the pipe is localized to one area such as a parking garage fire system, inspection of 80 or more examples of pipe is often possible within a single day. It requires approximately 8-10 minutes to perform UT measurement, photograph the pipe, and enter all data relating to its location and function into a laptop for each section of pipe. Multiple pipe sections within one local area will require less time each. Alternately, searching through an unknown building for a chill water line running behind locked doors with no site assistance can grind an investigation to a dead stop. Assistance from the building engineering staff, by removing and replacing insulation, providing ladders, assist navigation around the facility, identifying the location of piping systems, etc., is always helpful in moving along our progress, and is often the limiting factor to a successful investigation. The more quickly we can move throughout a facility and perform our intended function, the greater benefit to the client in gaining additional information and producing a more informative report. In cases where the building staff leaves for a smoke or bathroom break and disappears the rest of the day, far less is typically accomplished. Any of the below issues will typically reduce our progress resulting in either lesser work completed per day, or the need for additional time on-site.

- - Steam and high temperature piping
  - Heavily corroded surfaces
  - Cast iron & ductile iron pipe
  - Data centers
  - Insulated pipe
  - Excessive safety measures
  - Pipe requiring ladder and lift access
  - Excessive training requirements
  - Security restrictions
  - Residential access
  - Manhole / confined space

Question 11

What type of piping systems suffer the most due to corrosion?

Peter Plewa · Accepted Answer

In approximate order based upon our experience, the most troublesome piping systems are:

- - Condenser water
  - Perimeter dual temperature or chill water
  - Dry and pre-action fire sprinkler
  - Galvanized domestic water
  - Old cast iron sanitary waste pipe
  - New No-hub cast iron pipe
  - Steam condensate

We find far lesser problems at:

- - Wet fire sprinkler
  - Steam
  - Chill water mains
  - Hot water heating
  - Copper domestic water
  - Natural gas / fuel oil

Question 12

How is pricing calculated?

Peter Plewa · Accepted Answer

We have fixed daily fees generally dependent upon site location and travel distances.  Discounts are provided for larger investigations requiring multiple days of investigation.  Our basic rates consolidate the field testing, travel expenses, and time spent back in our office to analyze the data and produce the final report into one single fee.  Once outside the NJ / NY local area, additional charges for travel time and all travel expenses apply.  We typically provide a per day quote which incorporates two technicians, all travel costs, and the additional 4-5 days of data analysis and report preparation.  Where requested, we can provide a line by line breakdown of labor and fixed costs if needed.

Obviously, fees increase with distance, with projects in San Francisco carrying a higher fee than those in Boston or Chicago.  Still, a typical fee to travel to San Francisco and provide one day of field testing and address 50 examples of condenser water piping will likely equal the cost to physically cut out and metallurgically test just three actual pipe samples.

Question 13

Can we send you pipe to test?

Peter Plewa · Accepted Answer

Yes. Although one or a few pieces of removed pipe will not provide a representative view of the entire piping system, it is often a good first place to start an investigation. Generally, ultrasonic testing is no longer required once the pipe is removed and access to its cross section and interior is available for a direct dial caliper measurement. Nevertheless, we can still provide an analysis showing the same predictive information provided in a full report. Fees are fixed at $150 per pipe sample. For further information and detail on submitting pipe for testing please contact CorrView. We will provide provide recommendations related to saving samples, protecting them during shipping, and will provide a street address for shipping. Pipe samples will not be accepted by our Post Office Box address.

Question 14

How much pipe should be tested?

Peter Plewa · Accepted Answer

The answer depends upon the piping system, its condition, layout and configuration, pipe material, and many other factors. Generally, a full day of investigation during which 50 or more examples of pipe from one single piping system can be addressed will provide a very thorough assessment of piping condition for one piping system. Another important consideration is the need to prove an issue beyond debate, and to produce a report showing clear direction to follow. Wherever dispute exists regarding the condition of a piping system, and especially where litigation is even a remote possibility, additional testing should be planned in order to eliminate all possible debate to the results by all parties involved.

In a past investigation in San Francisco, one day of planned testing at a 32 story office building was insufficient to test every floor of a package unit based condenser water system. We provided building management the suggestion to choose even or odd floors in order to cover the full length of the property in the one day of allotted time, which we did. A report was presented two weeks later on all even numbered floors showing every single 3 in. threaded take off connection from both risers in severely deteriorated condition due to high galvanic activity caused by the brass valve. Our recommendation was to replace every single take-off from the main risers to the isolation valves, on all 32 floors, with dielectric fittings.

Two months later we were asked to return to San Francisco from New Jersey in order to test all odd numbered floor connections. Although we documented beyond any doubt that every single example of 3 in. run-out pipe on the even floors was near the point of failure, upper level managers had interpreted our report differently, and had reasoned that the odd floor piping was fine. Seeing no issues for the odd floors in the absence of hard proof, a critically important pipe replacement project was cancelled. Four weeks later, we returned to San Francisco to find every single 3 in. take-off section of pipe severely corroded and approaching failure, as one would reasonably assume.

Where a corrosion problem and pipe weakness is identified, additional time may be required in order to better define the extent of the weakness throughout the system, or to prioritize the greatest threat locations for more immediate corrective action. In general, we recommend testing an absolute minimum of 25 different locations for any specific piping system in order to produce a reliable piping assessment.

Question 15

We have a local UT company we like, but they cannot provide level of detail we want in your report.  Can you work together with them?

Peter Plewa · Accepted Answer

That is possible, maybe.  We have a written procedure for field testing in explicit detail, which, if followed by the UT tech, will provide us the necessary data in a format enabling us to produce a more informative piping assessment report.  However, virtually all past efforts have failed due to the raw data provided being inaccurate, due to other requirements of our procedure not being followed, or to other flaws or omissions in the information provided.  In the event we are able to work with a local UT company to assist with interpretation of data, CorrView International would not be held liable toward the accuracy of UT measurements or report.