Method of taking erosion/corrosion measurements

A method of taking erosion/corrosion measurements of a piping system for logging a history of the piping system over time comprises the steps of: (a) Wrapping a template about the pipe component; (b) Aligning the template with a reference marking on the pipe component; (c) Taking a wall thickness measurement at each of the spaced holes; (d) Recording at least the wall thickness measurement at each of the spaced holes and the indicia of the spaced hole location. The template extends circumferentially about the pipe component and has a plurality of spaced holes arranged in a grid pattern which holes extend through the template for receiving a probe for measuring wall thickness of the pipe component. The template has indicia for identifying each of the spaced holes.

FIELD OF INVENTION 
This invention relates to a method of apparatus for taking erosion and 
corrosion measurements of high pressure piping systems. In particular, 
this invention relates to the use of a template for taking consistent 
measurements for charting the history of a piping system over time. 
BACKGROUND OF INVENTION 
In industrial plants, piping systems for boilers, steam lines, liquid 
chemicals and the like are used to transport the materials from one 
location to another. The materials can be highly corrosive to the piping 
or can be transported under high temperatures and pressures which will 
cause extensive wear to the piping. Failure of the piping systems can be 
catastrophic in many instances, both in terms of environmental concerns 
and in terms of unscheduled emergency down time for a plant. 
Accordingly, systems have been developed to record the history of wear on 
the piping. A hand-held ultra-sonic thickness gauge has been developed for 
on-site data logging. The ultra-sonic gauge will measure the thickness of 
a pipe wall and record the measurement data in a memory together with 
other relevant information such as temperature, reading location and 
conversion. The data is downloaded onto a personal computer which then 
processes the data into an effective maintenance schedule and history of 
the plant piping system. Such systems are available under the trademark 
DML DL by KRAUTKRAMER BRANSON. 
In order to obtain an accurate history of measurements taken from the 
piping systems, the measurements must be taken from the same location so 
that wear from corrosion or erosion can be identified. If the measurements 
are not taken from the same location, false readings can be obtained which 
may result in accelerated repair schedules. 
The most common method of taking same location measurements is to place a 
grid pattern on the pipe component. The outside area of the pipe component 
is divided into a grid pattern. The size of the grid pattern can vary but 
many industries, such as nuclear utilities, have standardized the sizes. 
Grid sizes can vary from 1 to 6 inches (2.54 to 21.24 cm), depending on 
the size of the component which can vary from 2 to 30 inches (5.08 to 76.2 
cm). 
To commence an inspection, two persons normally will measure and draw the 
grid pattern on the component. A marker, paint, sticker or other marking 
device is used to scribe lines circumferentially around the component and 
axially along the length of the component. The spacing between all lines 
is maintained to as near the designated grid size as possible. Normally, 
it takes 6 to 20 person hours of labour to lay out and draw the grid 
lines. 
Once the grid lines are in place, the inspection can take place. An 
ultra-sonic probe takes a thickness measurement where the lines intersect. 
The data is stored for later analysis by the computer. 
A second method which is used is to place thin strips of a width of a 
corresponding grid size about the circumference of the component. The 
strips have a series of spaced holes 1/2 to 1/4 inch (1.27 to 0.635 cm) 
corresponding to the grid size used. Two persons place the strips about 
the component, attempting to maintain the grid size. As the strip is 
placed in the proper position, the hole positions are marked on the 
component using markers or spray paint. The strips are removed and then 
the readings using an ultra-sonic probe are taken and processed. 
Both of these methods are prone to errors in the layout of the grid and 
also of the inspectors in taking the readings. The inspector is required 
to trace each grid line or painted dot back to a starting reference point 
to determine the identification of the inspection point being measured. 
This results in the consumption of considerable inspection time which 
results in data which is not very accurate when repeating the inspection 
for a determination of wall losses at a future date. 
Further, it is quite common for the grid markings or painted dots to be 
missing for future inspections. Remarking is then required, which 
remarking is never in the exact location as the previous markings. 
SUMMARY OF THE INVENTION 
The disadvantages of the prior art is overcome by providing a method of 
taking accurate and consistent erosion/corrosion measurements by using a 
template having pre-drilled holes through which measurements are taken. 
It is further desirable to have a method of taking erosion/corrosion 
measurements where each location is identified for accurate recordal of 
measurement data. 
It is further desirable to have a method of taking erosion/corrosion 
measurements are repeated over a period of time at the exact location to 
provide an accurate history of the erosion/corrosion rate of wall 
thickness reduction. 
It is further desirable to have a method of taking erosion/corrosion 
measurements in a quick and efficient manner. 
According to one aspect of the invention, there is provided a method of 
taking erosion/corrosion measurements of a piping system for logging a 
history of the piping system over time, comprising the steps of: 
(a) Wrapping a template about the pipe component. The template extends 
circumferentially about the pipe component and has a plurality of spaced 
holes arranged in a grid pattern which holes extend through said template 
for receiving a probe for measuring wall thickness of said pipe component. 
The template has indicia for identifying each of the spaced holes. 
(b) Aligning the template with a reference marking on the pipe component. 
(c) Taking a wall thickness measurement at each of the spaced holes. 
(d) Recording at least the wall thickness measurement at each of the spaced 
holes and the indicia of the spaced hole location. 
In a further aspect, the method includes the step of repeating steps (a) 
through (d) over a predetermined period of time to log the history of wear 
of the pipe component. 
In a further aspect, a template is provided for taking erosion and 
corrosion measurements of a piping system for logging a history of the 
piping system over time. The template comprises a first half and a second 
half section adapted to wrap circumferentially about a pipe component of 
said piping system. The template has a plurality of spaced holes arranged 
in a grid pattern. The holes extend through the template for receiving a 
probe for measuring wall thickness of the pipe component. The template has 
indicia for identifying each of the spaced holes and has a reference 
marking for aligning the template with a reference marking on the pipe 
component. 
In a further aspect, the template is made from a material capable of 
withstanding temperatures of about 180.degree. C., preferably fiber glass. 
In a further aspect, the template has a first and second half faces 
releasably securable to the piping component and extending 
circumferentially thereabout.

DETAILED DESCRIPTION OF THE INVENTION 
The template of the present invention is illustrated in FIG. 1 as 10. 
Template 10 comprises a first half 12 and second half 14. First half 12 
and second half 14 mate with each other to fully surround the 
circumference of pipe 16. Template 10 can be of any length depending on 
the available space of piping 16 which is to be measured. 
The template 10 has an array of holes 18 extending through the thickness of 
the template 10. The array of holes is arranged in a grid pattern. The 
distance between holes or the grid size can be any distance provided the 
holes are spaced uniformly in both the axial and circumferential 
direction. Normally a grid size will vary from 1 to 6 inches (2.54 to 
21.24 cm), depending on the length of the component which can vary from 2 
to 30 inches (5.08 to 76.2 cm). Alternatively, a special grid size could 
be used on particular pipe components. 
Each hole has an indicia 20 to identify each hole. In this case, an 
alphabet letter is used to identify the axial position of the hole, while 
a numeral is used to indicate the circumferential position of the hole. 
Any method of coding the hole position would be suitable provided the data 
was being recorded and can be consistently processed to establish a 
history of the piping component. 
Second half 12 has a reference notch 22 at one end. Pipe 16 will have a 
reference mark 24 on the outer surface. Reference mark 24 can be any 
permanent mark on the pipe, such as a paint mark or a casted protrusion. 
Reference notch 22 is aligned with reference mark 24 to accurately 
re-install template 10 onto pipe 16. 
In FIG. 4, the template is illustrated as being arcuate in shape for 
fitting with an elbow shaped pipe component 116. The template comprises 
first half 112 and second half 114 and having a plurality of holes 118 
aligned in a grid pattern. Each hole 118 is marked with indicia in the 
same manner as the straight template 10. 
In the preferred embodiment, template 10 is made from a fiber glass 
material. Any suitable material may be used. However for high temperature 
piping systems, the template must be able to withstand temperatures in 
excess of 180.degree. C. Fiberglass is advantageous being light weight, 
rugged, durable and will not break under normal industrial use. Further, 
the smooth finish allows easy removal of couplants and contamination 
products. Fiber glass does not require heated storage and is not affected 
by weather or chemicals. 
In use, pipe component 16 is marked with a reference mark 24, if the pipe 
does not already include such a mark. Template halves 12 and 14 are 
wrapped about pipe component 16 and releasably secured to each other to 
extend circumferentially about pipe component 16. The reference notch 22 
of template 10 is aligned with reference marking 24. A plurality of spaced 
holes 18 arranged in a grid pattern extend about the circumference of the 
pipe component 16. A probe 26 for measuring wall thickness of the pipe 
component 16 is placed in one of the holes until it contacts the wall of 
pipe component 16. The template has indicia for identifying each of the 
spaced holes. Wall thickness measurements are taken at each of the spaced 
holes. 
The wall thickness measurement at each of the spaced holes and the indicia 
of the spaced hole location are recorded on a site file of an on-site data 
logger 28. 
The recorded data from the data logger 28 is then downloaded onto a 
personal computer which processes the data to create a history of the 
piping component. The history may be analyzed to form the basis to 
schedule routine maintenance on and replacement of the piping components. 
Alternatively, the thickness measurements and the location codes can be 
recorded manually on a manual recording report. 
The method of the present invention greatly reduces the time required for 
taking accurate thickness measurements. Due to the simplicity of the 
template, it may be installed and removed very quickly and easily. The 
possibility that an inspector will take improper readings is greatly 
reduced as the inspector does not have to continually identify grid lines. 
The measuring locations remain consistent from year to year and insures 
repeatability when inspection staff are changed. 
The above description relates to the preferred method by way of example 
only. Many variations on the invention will be obvious to those 
knowledgeable in the field, and such obvious variations are within the 
scope of the invention, whether or not expressly described.