DOCUMENT NO: ASTP 5008 VERSION: 2006-03-23 Page 1 of 5
TITLE: Standard Test Procedure for Measurement of Wall Thickness of Hose
Conduit, 30 CFR, Part 18
1.1. This document establishes MSHA’s Standard Test Procedure (STP) for
Measurement of Wall thickness of Hose Conduit, 30 CFR Part 18.
Information regarding the test instrument was extracted from ASTM D374-
79 and the RMA ISO DP4671 for the technical aspects of making hose
1.2. The purpose of the test is to describe the test procedures used to take wall
thickness measurements of hose conduit used in underground mines.
The Quality Assurance and Materials Testing Division, Approval and
Certification Center conduct the Hose Conduit Wall Thickness Measurement
3.1. This document supersedes CDS document ASTP4012 (dated: 1/01/85).
3.2. 30 CFR, Part 18, Section 18.39.
3.3. ASTM D374-79 - Standard Test Methods for Thickness of Solid Electrical
3.4. ISO 4671 - Rubber and Plastic Hoses and Hose Assemblies – Methods of
Measurement of Dimensions.
5.0 TEST EQUIPMENT
A micrometer as indicated in Section 4, ASTM D374-79 (Standard Test Methods
for Thickness of Solid Electrical Insulation) and having a ball attachment and
calibration markings in inches, readable to four decimal places should be used.
6.0 TEST SAMPLES
A three-foot sample of the hose conduit (submitted by the applicant) should be
used for wall thickness measurement.
7.1. Sample Preparation
7.1.1. The three-foot sample should be cut in two 1-1/2 foot sections and wiped
free of loose particles.
7.2. Sample Measurement: (See: Appendix A for schematic)
7.2.1. The sample should be measured at three locations:
18.104.22.168. A measurement should be made at each end of the hose conduit prior to
cutting. The measurement should be made ½-inch (12.7 mm) back from
the ends of the hose.
22.214.171.124. A measurement should be made ½-inch (12.7 mm) back from the end of
one hose section after cutting it in half.
7.3. Eight readings, symmetrically spaced around the circumference, should be
taken for hoses of 1-1/2” or less in diameter at each measurement location.
For hoses from 1-1/2” to 3” in diameter, 16 readings should be taken at each
measurement location. The readings should begin at the point where the
hose wall appears to be the thinnest, by visual observation. For small
diameter hose, it may be necessary to split the sample to insert the
7.4. The micrometer jaws should be opened wide enough to freely insert the
sample, then closed slowly using the friction sleeve until it slips and the
reading does not change. The ball attachment should be placed against the
inside of the hose.
7.5. Record each reading on the hose conduit wall thickness test form (See
Appendix B) to four decimal places after subtracting 0.2000 for the ball
attachment. Indicate the minimum thickness reading and calculate the
overall average thickness from the sum of all the measurements.
7.6. Precision of Method
7.6.1. The precision of this method is considered to be limited to 0.0075 inch due
to possible squeezing of sample, presence of dust particles and accuracy of
7.7. Test Modifications
7.7.1. Since all possible materials / products, compositions, physical properties,
and applicable methods cannot be foreseen, MSHA reserves the right to
modify the above test procedures.
8.0 TEST DATA
A photograph of the conduit sample showing measurement locations (A, B, C)
should be taken for documentation. The test data on the conduit sample is
recorded on the laboratory data sheet shown in the Appendix B. The data sheet
and photograph are then included in the record files.
9.0 PASS/FAIL CRITERIA
The hose conduit should be deemed in compliance with the wall thickness
criteria of CFR 30, Part 18, Section 18.39 (3/16” = 0.18750 inch minimum) if the
overall average measurement is not less than 0.1800 (0.1875 - 0.0075) inches.
However, if the test data show the hose sample is not uniformly round
(concentric) and at least one (1) measurement in each of the three (3) sample
measurement locations is less than 0.1800 (0.1875 - 0.0075) inches, the hose
should be considered as not being in compliance with Section 18.39 (3/16” inch
ASTP5008.doc Print Date: 3/29/2006
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UNCONTROLLED. VERIFY CORRECT VERSION PRIOR TO USE. TSTP0001, Rev 01