Interpretation Response #PI-81-0105
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
May 1, 1981
Mr. Leo Effenberger
500 Simpson Avenue
P.O. Box 1167
Elkhart, IN 46515
Dear Mr. Effenberger:
In regard to your letter of April 14, 1981, it is the policy of this office not to sanction vendors
of pipeline materials. We will be happy, however, to answer any remaining questions you or your
clients may have regarding compliance with §§192.147 and 195.126.
Melvin A. Judah
Acting Associate Director for
Pipeline safety Regulation
Materials Transportation Bureau
500 SIMPSON AVENUE P.O. BOX 1167
ELKHART, IN 46515
April 14, 1981
Mr. Melvin Jadan
Acting Assoc. Director of Pipeline Regulations
Department of Transportation Materials Transportation Bureau Washington, DC 20590
Dear Mr. Jadah:
Your office in September, 1977 issued an opinion to our representative that stress analysis and
proof testing to VG-101 would be sufficient to qualify our convoluted flange for use under Section
192.147 and 195.126. I am enclosing that required documentation and requesting correspondence from
your office that we are a qualified vendor for flanges under that section. We have several gas
companies that will use our product only with this qualification letter from your office.
Leo Effenberger, P.E.
National Sales Manager
DEPARTMENT OF TRANSPORTATION MATERIALS TRANSPORTATION BUREAU WASMNGTON, D.C. 20590
September 21, 1977
Mr. Gunter Schlicht
One Northwood Drive #5
Orinda, California 94563
Dear Mr. Schlicht:
Your letter of July 7, 1977, requests an interpretation of the applicable requirements of Parts 192
and 195 relating to the design and testing of pipeline flanges. Your specific question is: are the
requirements of the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 (Boiler Code)
considered as an equivalent as intended in Section 192.147 to the referenced specifications for
flanges in Part 192? Also, does the Boiler Code meet the requirements for flanges of Section
195.126 in Part 195?
The Boiler Code, which is referenced in both Parts 192 and 195, and the ANSI B16.5 and MSS-SP-44
specifications that are referenced in Part 192 are intended for the conventional design flanges
that would be manufactured by casting or forging rather than the convoluted design that would be
In Appendix II, Paragraphs UA-45 thru UA-59, inclusive, of the Boiler Code, the procedure for
designing flanges for manufacture by casting or forging is set forth. It is suggested in this
Appendix that if the procedure set forth is not appropriate for the design, then in order to
establish allowable working pressures, the flange should be proof tested under the provisions of
the Boiler Code, Section UG-101, Proof Tests, to establish maximum allowable working pressure. The
testing required by UG-101, that is applicable to all pressure vessels, is more severe and thorough
than that required by any of the other referenced specifications for flanges.
It is our opinion that a detailed design and stress analysis supported by a proof test under the
UG-101 of the Boiler Code provides the equivalent level of safety intended by Section 192.147.
Section 195.126 states, with respect to a flange connection, that the "connection as a unit must be
suitable for the service in which it is to be used." It does not provide any standard or test
method to be used to determine the suitability.
It is our opinion that the stress analysis and Boiler Code testing under the provision of UG-101
would be sufficient to determine whether flange connections are suitable under Section 195.126.
Cesar DeLeon Acting Director Office of Pipeline Safety Operations
THOMAS A. SHORT CO.
3430 Wood Street
Oakland, California 94608
November 8, 1978
500 Simpson Avenue
Attention: Mr. Bob Russell
Dear Mr. Russell:
This letter verifies that the below listed convoluted NIBCO flanges, Class 150, were
hydrostatically tested in our facility on September 20, 21, 22 and October 27, 1978.
TEST PURPOSE To establish working pressure ratings for NIBCO convoluted Class 150 flanges in sizes
and types indicated in the tables below in order to satisfy Section VIII, Div. I UG-101 proof test,
and Section 1, Div.
1 PG-100 Proof Test (ASME Pressure Vessel Code).
TEST SPECIMENS NIBCO convoluted flanges, Class 150, were mounted to conventional ANSI B16.5 blind
flanges, class 150, raised face with standard serration. Bolting material consisted of A-193 B16
studs with grade 4 nuts, lubricated with anti-seeze lubricant. Gasketing material consisted of
1/16" thick standard compressed asbestos sheets and/or line backers.
The conventional ANSI B16.5 blind flanges were center drilled and tapped with 3/4" NPT in order to
fill the specimen with water through this opening and remove the entrapped air and to connect the
hydrostatic pressure test system. All flanges were identified per MSS-SP25.
GENERAL STATEMENT Each pressure test was terminated at point of gasket leakage or gasket blowout
and not at the metallic burst pressure level of the component (flange) under evaluation. Three
types of flanges were tested. Specific descriptions relating to the flange type preceeds the
A) NIBCO Convoluted Weld Neck Flange, Class 150, ASTM A316-60
The weld neck flanges were welded to standard wall, black steel pipe on one end while a standard
wall B16.9 weld end cap was welded to the other end. The pipe length represented a minimum length
of two times the diameter of the nominal flange connection size.
Test Results: Size Max hydrostatic Pressure PSI Leak
2” 3500 no
2-1/2” 3500 no
3” 2200 yes
1” 2400 yes
5” 2600 yes
6” 1900 yes
8” 2000 yes
10” 2200 yes
B) Convoluted Blind Flanges, Class 150, ASTM A-516-60 The convoluted blind flanges were mounted
directly to convoluted ANSI B16.5 raised face blind flanges.
Test Results: Size Max hydrostatic Pressure PSI Leak
2” 4200 yes
2-1/2” 3800 yes
3” 2600 yes
4” 2800 yes
5” 2700 yes
6” 2000 yes
8” 2000 yes
12” 1900 yes
C) Convoluted Lap-Joint Flanges, Class 150, ASTM A-36 The convoluted lap-joint flanges were
slipped over a conventional standard wall stub end type "A" to which a piece of standard wall black
steel pipe was welded, plus a standard wall B16.7 weld end cap. This entire assembly was mounted to
816.5 raised face standard serration blind flange.
Test Results: Size Max hydrostatic Pressure PSI Leak
1” 4000 no
1-1/2” 3700 yes
2” 4100 yes
2-1/2” 3950 yes
3” 3500 yes
4” 3000 yes
5” 2800 no
6” 2550 yes
All welding of the test specimen were performed by Scott Company of Oakland, California. The tests
were assembled and performed by the THOMAS A. SHORT CO. under the personal supervision of Bill
Sutliffe. The tests were witnessed by:
Very truly yours,
Gerald Horn, Safety Engineer D.I.5 838, N.B. 4663
Pressure Vessel Section
Division of Industrial Safety Department of Industrial Relations State of California
Gunter Schlicht, President
Pipetech, Inc. Orinda, California
R.M. Johnson, Manager Contracting and Repairs
STRESS ANALYSIS OF PIPETECH FLANGE PROFILE #14
The purpose of this analysis was to determine stresses and displacements of profile #14 Pipetech
flange when subjected to both bolt load and hydrostatic pressure.
The flange was modeled as a body of revolution with loads applied to simulate the bolt and
hydrostatic pressure. A linear elastic static analysis was conducted.
The analysis was conducted with the computer program MARC-CDC. MARC-CDC is a finite element
computer program used for structural analysis. The program is widely used for structural analysis
and design of nuclear facilities. Westinghouse, General Electric, and Bechtel Corporation are some
of the many firms that have used the program. The program is available at all Control data
Corporation data centers throughout the United States. All analysis was conducted on the CDC-6600
computer at the Western Cybernet Center at Sunnyvale, California.
DESCRIPTION OF ANALYSIS TECHNIQUE
The Finite Element Technique is a numerical procedure which can be used to compute displacements
and stresses in structures of arbitrary geometry subjected to various loading conditions. Solution
is obtained by the following steps:
• Break the structure up into individual elements interconnected by nodal points.
• Describe the location of the nodal points by specifying the coordinates of each point.
• Describe the elements by indicating the nodal points connected to them and the material
(E,") associated with them.
• Specify the applied loads and indicate which nodal points are not free to move.
The finite element program then takes the input geometry, material properties, and load description
and calculates displacements at the nodal points and stresses at the center of each element. The
mathematical techniques employed in the solution are based on the principles of solid mechanics.
Details of the calculations can be found in O.C. Zienkiewicz, The Finite Element Method in
The flange was modeled as showing in fig. 1. Four elements were used through the thickness.
Node and element numbers are shown on the mesh. R and Z components of displacement are calculated
at each nodal point in the model, while stresses are calculated at the center of each element.
Radial, axial, hoop, shear, and von Mises stress are calculated for each element.
Rollers which prevent axial motion (z-direction) were placed at the free end, node 5, and at the
gasket, nodes 145, 150, and 155. Nodes 226-230 were not constrained. This was felt to be a worst
case condition for the flange pipe connection.
Pressures were applied to simulate the bolt load over elements 45, 46, 47, 48, and 49. Pressures
were applied over elements 116, 117, 133, 134, 135, 136, 137, 153, 154, 155, 156, 157, 158, and 159
to simulate hydrostatic pressure. The input load description is shown in Table 1.
Bolt Load = 11,300 lbs/bolt
Total Bolts = 12
Contact Area = p(9.942 – 8.8152) = 66.286 in2
Bolt Pressure = (number of bolts)(bolt load) Contact area
= (12)(11,300) = 2045 psi
Also subjected to a hydrostatic pressure of 285 psi.
Steel: E = 30 x 106 psi
The contour plot of the von Mises stress is shown in Figure 2. The von Mises stress was calculated
the following formula:
svon Mises = v ½ (szz -sRR)2 + (sRR -shoop)2 + (shoop -szz)2 + 3s2 RZ
For a ductile material such as steel, the von Mises stress can be compared directly with the
allowable stress specified for the material. For this loading a maximum von Mises stress of 12, 770
psi occurs in Element
47. Note that stresses are calculated at the center of the elements and must be extrapolated to get
values at the surface.
I have also included the stresses computed for each element and the calculated nodal point
METALLURGICAL AND MECHANICAL EVALUATION OF 3", 4", AND 6” FLANGES
HASKELL D. WEISS, P.E.
This report presents and evaluation of three flange parts (3", 4", and 6") and a portion of a plate
of starting material prior to cold forming.
Sections were removed from parts by sawing and/or flame cutting and then prepared for study by
polishing and etching.
The analysis was made with the aid of a metallurgical microscope and a microhardness tester. The
report sections cover in detail the following:
1) Metallurgical examination of starting material.
2) Metallurgical examination of 3”, 4", and 6” diameter flanges.
3) Deficiencies that should be corrected.
4) The effect of welding on flange material.
5) Product reliability and heat treatment. DISCUSSION
1. The starting material is cross-rolled and has a reported chemical content by weight of: C
Mn - .74%
P - .006%
S - .015% Si - .22%
Fe - balance
To obtain a fine grain it is rare earth treated. It has not as yet been determined if production
parts will be pickled, grit blasted or surface treated in some fashion prior to forming. To prevent
inbedding of foreign materials during drawing it is suggested that starting plate be cleaned prior
A sample was removed from the starting stock as per Fig. 1. Fig. 2 and Fig. 3 show the
microstructure in both longitudinal and transverse directions. The grain size and elongation show
that rolling was about equal in each direction. The dark regions are pearlite and the light regions
are ferrite. Reported tensile data:
Yield Strength ------- 45,000 psi
Tensile Strength ----- 66,000 — 72,000 psi
Elongation in 8" ----- 26.5 — 28.2%
Microhardness tests were made on both center and edges of the plate as shown in Fig. 4. The
hardness numbers in DPH were converted to Brinell and tensile strength.
DPH BH Tensile Strength (psi) Edge 171
Center 150 143 71,000
This agrees quite well with the reported data, also it indicated the strength is uniform throughout
It is important that in future purchases of starting stock that this uniformity of microstructure
be maintained. Lack of uniformity could lead to differences in springback from one lot of material
to another. Additionally lack of uniform texture could cause failure in forming.
2. There were three flanges examined; a 3", 4" and 6" diameter type. These are formed in
multiple draw operations. The tooling concepts may be different between sizes. However, each type
is treated as a single population and die design differences are not relevant to the conclusions
The drawing sequences are done at ambient temperature conditions with no anneal, stress relief or
heat treatment of any type performed on the final formed parts. Thus, the microstructures are
representative of production parts.
Fig. 5 shows a 3" blind flange in section and location of microhardness readings and orientation of
grain structure examination. Fig. 6 and Fig. 7 shows the variation in cold work areas "k" verses
"n". Areas "a" and "c" are shown in Fig. 8 and Fig. 9. These show laps and heavy deformation
resulting from the forming operations. Note that in heavily deformed regions the identity of the
grain structure is almost lost. Also note the depth of heavy deformation appears to be
approximately .010" to ,015".
From reference (1) it is noted that steel typical of this composition has a true strain at fracture
of between .9"/" to 1.0"/". This can be transformed into the cold work capacity which amounts to
60%. (Reference 1)
The microhardness in the various areas are tabulated and converted into tensile strength and cold
work percentage, Table 1. From these numbers and the microstructure and assessment of the part can
Fig. 10 shows a 4" flange in cross section and location of areas of investigation. Fig. 11 and Fig.
12 of areas "c" and "i" are typical of the microstructure. Note the diamond penetrator mark in Fig.
11, indicating measurements of cold worked areas within .005" of the surface. See Table 2 for
hardness, cold work and tensile strength. The microstructural examination shows no evidence of
laps, seams or tears.
Fig. 13 and Fig. 14 shows a 6" blind flange and the section removed for examination. Fig. 15 and
Fig. 16 shows areas "a" and "c" where a lap and tear are evident. The hardnesses and cold work are
listed by area in Table 3.
Comparison of the three flanges by microstructure and cold work would indicate the 4" to have the
least amount of surface deformation. The areas of maximum work, 3" and 6", show where metal has
been cold worked as high as 57%. This heavy amount of cold work however, measures less than .015".
3. If the 4” flange were to serve as a standard, then the surface of all parts should
be continuous without tears or laps. From a cosmetic standpoint this would be desirable, however
from a reliability standpoint it is not necessary, as will be discussed in section 5. What is
needed is reproducibility and quality control.
4. In the upper portion of Fig. 14 is shown an almost straight section. The right edge
at the arrow indicates a region where the part was flame cut to separate from the balance of the
flange. Note the shade difference at the right. This indicates the recrystallized zone due to
oxy-acetylene flame cutting. This region also appears during a welding operation. Fig 17 shows two
different structures in the heat affected zone
(HAZ), note Fig. 18 which shows a microstructure typical of the starting material. Working through
of melt zone and HAZ, the distance involved amounts to .180". This would indicate that the heat
an electric arc would not affect the parent material beyond a distance, conservatively with
of .30" from the molten edge. Note that the hardnesses are higher in region "u", Fig. 17, then in
material, (Table 3). This results from the rapid cooling of the HAZ allowing for a finer grain
Generally, strength increases with decreasing grain size.
The above would suggest that welding will not degrade the strength of the worked parent material.
Generally, the weld metal is the weakest link in any structure, since it has a cast, course grained
microstructure. This, as a rule, is compensated for by increasing the cross sectional area of the
5. In the absence of long term test data on fully stressed flanges, assumptions and
conservative estimates are necessary in order to present a credible reliability statement. A review
of the stages in the drawing of a 3" diameter flange indicates that there are three stages
involved. The state of stress varies not only throughout the part but through the thickness as
well. As indicated earlier the heavy deformation is
limited to approximately .015”. Biaxial stresses exist throughout the part and are generally in
tension radially and in compression circumferentially. A feel for the magnitude of these stresses
are indicated by the hardness readings when converted to percentage cold work. The presence of
biaxial stresses can be noted by Fig. 19 which is taken in the area between "a" and "c". Note the
elongation of grains perpendicular to the surface, as opposed to the grains in Fig. 12 which are
parallel to the surface. This would tend to indicate compression at the surface in many locations
would inhibit the tendency for fatigue cracking.
In my opinion 40% cold work is a tolerable level for parts so long as this amount is kept within
.020" of the edge. However, in the 3" and 6" flange this is exceeded not in depth but in magnitude.
the significance of region "c" in Fig. 9, I assumed that a part had a fatigue crack .015" and
cyclic stresses of 10
KSI (Appendix). This calculates to a part life of 5.5 x 106 cycles. Other stresses, fatigue crack
lengths and cyclic life are tabulated in the Appendix. These results show fatigue is not a problem
at the selected design loads and defects limited to .015". I have arbitrarily selected 5.4 x 106
cycles as infinite life. This calculation assumes an infinite thickness of plate. Obviously, this
is not true, also the effect of corrosion products on fatigue cracks has not been taken account of
in the calculation. For this reason, I have been conservative in my estimates and believe the above
crack limitation and stresses are realistic.
It should also be pointed out that high hardness on the surface has a somewhat similar effect
relative to fatigue resistance as that of shot peening. While, the material below the heavy
deformation has an extremely high toughness, or fatigue resistance. Therefore, I do not believe it
is either necessary to anneal or shot peen the flange surfaces. Quality control should be exercised
to limit sharp tears to a maximum of .015” or approximately 5-10% of the part thickness. Dents as a
result of handling are not a problem so long as they do not result in sharp cracks. This is a
materials handling problem faced by all users of any structural piece of hardware.
The inspection techniques can be a combination of "Magnaflux" and dye penetrant. The latter can,
with experience, be developed to provide a quanitative estimate of the depth of surface flaws.
Starting material should be randomly (1) mechanically tested; (2) grain size checked; (3)
chemically analyzed; (4) and hardness tested. All of the above is directed toward the use of a
controlled starting material. A lowering of reduction of area; increase of grain size; differences
between longitudinal and transverse grain structure could cause the manufacturing process to become
out of control and parts not meet specification.
1. "Material Properties and Manufacturing Processes", J. Datsko, John Wiley and Sons, 1967.
2. "Linear Elastic Fracture Mechanics and Its Application to Fatigue", R.I. Stephens, Society
Engineers, 740220, 1974.
c (lap Area)
a x d (center)
e (center) f (edge) f(edge)
f (center) g (edge) h (edge)
g x h (center) g x h (center) I (edge)
j (outside edge) k (inside edge) n (outside)
n(center) n (inside) n (inside)
Cold Work (%)
c d e f g h i
j j k
Cold Work (%)
Region Hardness (DPH) (Hardness (BH)
T.S. Cold Work (%)
a (HD)* 284 270
134 (KSI) 46
a (LHD)* 287 273
135 46.6 a (NHD)* 261
a (HD)* 377 357
178 59.5 c (HD)* 394
c (LHD)* 348 329
164 56 c (LHD)* 322
52 c (NHD)* 287 273
134 46 cf
277 262 130
44 f 232
221 107 32 cf
e 214 204
98 26.5 e 261
ee 254 242
119 38 o 270
43 n 322
306 152 52 n
119 39 n 290
46 nn 239 228
110 36 i
277 262 130
44 h 277
262 130 44
g 259 245
120 39 gh 276
|§ 192.147||Flanges and flange accessories|