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Interpretation Response #PI-81-0105

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name:

Individual Name:

Location State: IN Country: US

View the Interpretation Document

Response text:

PI-81-0105

May 1, 1981
Mr. Leo Effenberger
Nibco Inc.
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.
Sincerely, SIGNED
Melvin A. Judah
Acting Associate Director for
Pipeline safety Regulation
Materials Transportation Bureau

NIBICO INC.
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.

Sincerely,
Leo Effenberger, P.E.
National Sales Manager
Industrial Division

DEPARTMENT OF TRANSPORTATION MATERIALS TRANSPORTATION BUREAU WASMNGTON, D.C. 20590

September 21, 1977

Mr. Gunter Schlicht
Pipetech, Inc.
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
folded into
shape.

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
provisions of
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.

Sincerely
Cesar DeLeon Acting Director Office of Pipeline Safety Operations

THOMAS A. SHORT CO.
3430 Wood Street
Oakland, California 94608

November 8, 1978

NIBCO Inc.
500 Simpson Avenue
Elkhart, Indiana
46514

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
associated table.

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
                Torque Ft.-lb.
2”                                   3500                                            no             
                     100
2-1/2”                            3500                                            no                
                  110
3”                                   2200                                            yes            
                    125
1”                                   2400                                            yes            
                    150
5”                                   2600                                            yes            
                    190
6”                                   1900                                            yes            
                    200
8”                                   2000                                            yes            
                    270
10”                                 2200                                            yes             
                   500

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
                Torque Ft.-lb.
2”                                   4200                                            yes            
                    100
2-1/2”                            3800                                            yes               
                 110
3”                                   2600                                            yes            
                    125
4”                                   2800                                            yes            
                    150
5”                                   2700                                            yes            
                    190
6”                                   2000                                            yes            
                    200
8”                                   2000                                            yes            
                    330
12”                                 1900                                            yes             
                   600

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
an ANSI
816.5 raised face standard serration blind flange.

Test Results:                 Size                   Max hydrostatic Pressure PSI              Leak
                Torque Ft.-lb.
1”                                   4000                                            no             
                     .35
1-1/2”                            3700                                            yes               
                 45
2”                                   4100                                            yes            
                    120
2-1/2”                            3950                                            yes               
                 125
3”                                   3500                                            yes            
                    140
4”                                   3000                                            yes            
                    150
5”                                   2800                                            no             
                     190
6”                                   2550                                            yes            
                    200

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,

Bill Sutliffe
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
and:
Gunter Schlicht, President
Pipetech, Inc. Orinda, California

R.M. Johnson, Manager Contracting and Repairs

STRESS ANALYSIS OF PIPETECH FLANGE PROFILE #14

R.C. Murray
May 1976

INTRODUCTION

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
properties
(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
Engineering Science.

MODEL DESCRIPTION
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.

TABLE 1
Input Loading
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
66.286
Also subjected to a hydrostatic pressure of 285 psi.

Material Properties
Steel: E = 30 x 106 psi
"=0.3

RESULTS
The contour plot of the von Mises stress is shown in Figure 2. The von Mises stress was calculated
by
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
maximum
values at the surface.

I have also included the stresses computed for each element and the calculated nodal point
displacements.

METALLURGICAL AND MECHANICAL EVALUATION OF 3", 4", AND 6” FLANGES

HASKELL D. WEISS, P.E.
MT431

INTRODUCTION
This report presents and evaluation of three flange parts (3", 4", and 6") and a portion of a plate
typical
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      
   -           .18%
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
to working.

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         
         162                                 79,000
Center              150                   143                                 71,000

This agrees quite well with the reported data, also it indicated the strength is uniform throughout
the thickness.

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
drawn.

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
between 50-
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
be made.

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
the regions
of melt zone and HAZ, the distance involved amounts to .180". This would indicate that the heat
generated by
an electric arc would not affect the parent material beyond a distance, conservatively with
multipass welding,
of .30" from the molten edge. Note that the hardnesses are higher in region "u", Fig. 17, then in
the starting
material, (Table 3). This results from the rapid cooling of the HAZ allowing for a finer grain
structure.
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
weld metal.

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
.010-
.020" of the edge. However, in the 3" and 6" flange this is exceeded not in depth but in magnitude.
To assess
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.

REFERENCES

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
of Automotive
Engineers, 740220, 1974.

Region

a (edge)

a (edge)

c (lap Area)

c (edge)

d (edge)

d (edge)

a x d (center)

e (edge)

e (edge)

e (center) f (edge) f(edge)
f (center) g (edge) h (edge)
g x h (center) g x h (center) I (edge)
I (edge)

j (center)

j (center)

j (outside edge) k (inside edge) n (outside)
n(center) n (inside) n (inside)

Hardness(DPH)

353

348

366

305

252

255

241

263

272

245

266

252

243

285

322

255

256

287

290

223

237

226

323

228

241

258

250

Table 1
Hardness (BH)

334

329

347

289

240

243

228

250

258

233

252

240

231

270

306

243

244

273

275

212

225

215

306

217

228

245

238

T.S. (KSI)

168

164

173

143

117

119

112

123

127

114

124

117

113

134

152

119

120

134

136

102

109

104

153

105

112

120

116

Cold Work (%)

56

57

49

37.5

39

35

41

42

36

41

37.5

35

46

52

39

39

46

46

28

33

30

52

30

35

39

37

Table 2

Region a
c d e f g h i
j j k
m

Hardness (DPH)

221

225

252

232

223

254

250

277

247

255

265

263

Hardness (BH)

210

214

240

221

212

242

238

262

235

243

252

250

T.S. (KSI)

101

103

117

107

102

119

116

130

115

119

124

123

Cold Work (%)

28

29

37.5

32

28

38

37

44

36

39

41

41

TABLE 3
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               
                       247                                       121                               
        40
a (HD)*                    377                                       357                            
          178                                       59.5 c (HD)*                    394            
                          373                                       187                            
           61
c (LHD)*                  348                                       329                             
         164                                        56 c (LHD)*                  322               
                       306                                       153                               
        52 c (NHD)*                 287                                       273                  
                    134                                        46 cf                              
277                                       262                                       130             
                          44 f                                232                                  
    221                                       107                                        32 cf     
                        232                                       221                              
        107                                        32
e                               214                                       204                       
               98                                         26.5 e                               261
                                     247                                       121                 
                      40
ee                             254                                       242                        
              119                                        38 o                               270    
                                  256                                       126                    
                   43 n                               322                                       
306                                       152                                        52 n           
                   256                                       243                                   
   119                                        39 n                               290               
                       275                                       136                               
        46 nn                             239                                       228            
                          110                                        36 i                          
      277                                       262                                       130      
                                 44 h                               277                            
          262                                       130                                        44
g                               259                                       245                       
               120                                        39 gh                             276    
                                  262                                       130                    
          &#

Regulation Sections

Section Subject
192.147 Flanges and flange accessories