Responses to Technical Interpretations


Request Date: 05/31/2018

My question is in regards to the interpretation of the dimensional annotations throughout the specification. Specifically; the interpretation of trailing zero's in respect to the typical rounding rules of math. For example: Table 2 on page 11 of the referenced specification defines the tolerances and minimum wall thicknesses. In several dimensions those numbers may be expressed in two (2) decimal place notation or in three (3) decimal place notation. Such as 1/4 NPS, Socket Depth Tolerance = +/- 0.03 and Class 200 Socket ID = +/-0.015. If I do not use standard rounding, then I can interpret these dimensions to possess infinite trailing zero's i.e., such as ¼ NPS, Socket Depth Tolerance = +/-0.03000000000 and so on and Class 200 Socket ID = +/-0.0150000000 and so on. If I employ standard rounding, then I can interpret these dimensions as follows: 1/4 NPS, Socket Depth Tolerance = +/-0.03 rounded to the nearest 1/100th and Class 200 Socket ID = +/-0.015 rounded to the nearest 1/1000th. The primary reason for this request is that if I measure the socket depth for the above example, nominal depth + 0.031, how do I interpret this result. Do I round the socket depth and accept the fitting or do I not round the socket depth and reject the fitting?

Answer Date: 07/31/2018


The tolerance dimensions that are stated in MSS SP-119-2003 are the limit dimensions for manufactures and there is no rounding applied. The Socket Depth “B” (Table 3) is stated in 1/100 inch and Socket Depth “B” Tolerance (Table 2) is stated to the same degree of accuracy for the manufacturing of product specified to SP-119-2003. The Socket Inside Diameter “C” for Class 200 (Table 3) is stated in 1/1000 inch and the Socket Inside Diameter “C” for Class 200 Tolerances (Table 2) are, again, stated to the same degree of accuracy for the manufacturing of product specified to SP-119-2003.


Request Date: 06/26/2018

In determining production shell test times, the chart (Section 10.1, page 6) establishes durations based on designs shown in subsequent figures (pages 12-14). However, there is confusion as to how to classify a product which may fall into more than one of those figures simultaneously and thus to what duration it should be tested. For example, if a BFV has an integral flange gasket (Figure 1B) but is also single flanged or flangeless (Figures 3 & 4), should it test in accordance with durations based on its face-to-face design (Figures 1A, 1B, or 1C) or its bolting options (Figures 2, 3, 4, 5, or 6)?

Answer Date: 07/18/2018


The confusion results from Figures 2, 3, and 4 included within Column 2. These figures, showing bolting options, should not be included as they are not relevant to the shell test. Only the end connections and the method for sealing should be considered. As such, Figures 1B, 5, and 6 should be in Column 1 and Figure 1A and 1C should be in Column 2. Figures 2, 3, and 4 should not be considered for the shell test.

Request Date: 06/26/2018

In Section 10.1, production shell testing, it states that "Leakage through the shaft seal shall not be cause for rejection."

Is this only for shaft seals which are adjustable or can be tightened, or for any shaft seal design?

Answer Date: 07/18/2018


The statement in Section 10.1 cited by the inquirer only applies to shaft seals that are adjustable or can be tightened. However, the manufacturer shall demonstrate that all shaft seals are capable of retaining a seat test pressure of 1.1 times the rated cold working pressure (CWP). If non-adjustable shaft seals such as O-rings or fixed single rings are used, then shaft seal leakage is not permitted during shell and seat tests. Note: The committee chair will address these matters with the committee and a revised document or other corrective action may result.


Request Date: 08/18/2016

The qualification section speaks to Radiation aging "to the requirements of the Design Specification or a dose level equivalent to the service life, as specified in Section 4.0." Does there need to be information as to qualification information that would address those applications used inside containment for an accident dose?

Answer Date: 10/17/2017


Answer: The initial response previously provided (see Attachment 1) was determined to be adequate and it is advised that this issue is not covered by MSS SP-100 at this time.

Note that the issue was further discussed during the 2017 TC-406 meeting and was determined that because the data related to accident dosage is not well defined in the industry and varies significantly from one customer to another, that no immediate changes to SP-100-2015 are necessary. However, a Task Group within TC-406 has been established to further address the issue in preparation for the next review cycle and subsequent edition.

Attachment1: It is believed you make a valid point, in that there is nothing in SP-100 that covers the application where a diaphragm may be subject to an accident dose of radiation. SP-100 currently provides guidance for normal operation of a diaphragm valve in a Nuclear plant that is subject to radiation dosages consistent with a typical radioactive environment. However, for those special cases where a customer has a requirement for a valve to continue to operate after a one-time accident dose (which is usually quite large), SP-100 does not yet account for that. SP-100 has served us well for a number of years because while many sites use diaphragm valves in Nuclear service, not every site has accident dose requirements. Complicating things greatly is the fact that every site seems to have their own accident dose requirements concerning duration, magnitude, and expectation of the diaphragm after the accident has occurred (i.e., must the valve still be able to shut off against operating pressure and temperature, or does it just need to function as a gasket? Does it need to be able to cycle once or twice or a full year’s worth of cycles and still shut off?). Accounting for inside containment / accident dose conditions per this request would be complicated.

It is advised that this issue is not covered by SP-100 at this time. However, due to your request, the committee will address this matter at its next meeting to determine if SP-100 should be revised to account for this issue during its next review period. This request will be considered an open Official Inquiry until the 2017 Committee 406 meeting and the result of committee discussions will be processed by the Executive Director and separately by the committee with regard to any potential revisions.


Request Date: 09/19/2016

1. Interpretation of Stress Relieving Treatment on copper nickle fittings: 15.3 Copper nickel fittings shall be stress relieved, except as allowed in Section 15.1. Heat treating shall be performed at 1300 +/- 50 °F for one hour at temperature per inch of thickness. We interpret the temperature given, as the temperature of the oven and not of the fitting.

2. Interpretation of Concurrent Fitting Qualifications of Different Sizes and Types: 7.3 ...In addition, tests performed on belled end fittings qualify street end fitting of the same geometry and manufacturing method. We interpret this to mean that it will also cover the same ranges of size as the belled end fittings, one half to twice the size of the size the test was performed on for the belled end fitting.

3. Interpretation on Manufacturing Method Proof Testing: MSS SP-119 does not make any distinction between MIL-T-16420 pipe Type I (Seamless) and Type II (Welded), so we interpret that a successful manufacturing method proof test on Type I pipe will qualify Type II pipe and vice versa, granted the manufacturing method is the same.

Answer Date: 09/07/2017


1. Yes

2. Yes

3. Yes


Request Date: 11/29/2016

1. Is MSS SP-58-2009 Pipe Hangers and Supports intended to apply to creep strength enhanced ferritic steel (ASME P-No.5B) materials, such as ASTM A387 Grade 91, listed in Table A2/A2M?

2. MSS SP-58-2009 Pipe Hangers and Supports tables A2/A2M contains allowable stress values for ASTM A387 Grade 91, but does not specify the "Condition". Do the allowable stress values provided in Tables A2/A2M represent material in the normalized and tempered condition, as required by Section 5.1.1 of ASTM A387 for Grade 91?

3. Is Section 12.3.1 the only place throughout MSS SP-58-2009 where heat treatment is required after forming?

4. Is heat treatment after hot forming of ASTM A387 Grade 91 required?

5. MSS SP-58-2009 Section 12.3.2 Hot Forming specifies a range of 1550F to 2000F for Chrom-Moly Alloy Steel. Does this apply to ASTM A387 Grade 91?

6. Has MSS SP-58-2009 considered these potential damaging effects to creep strength enhanced ferritic steel materials, such as ASTM A387 Grade 91, anywhere in the standard?

Answer Date: 01/04/2017


1. Yes, The temperature range of allowable stresses is identical to ASME B31.1, which includes the creep/stress rupture range for ASTM A387, Grade 91.

2. Yes

3. No, Section 12.3.3 also adresses heat treatment after forming.

4. No, Section 12.3.3 does not explicitly require or exclude heat treatment after hot forming. The requirements for heat treatment should be based on project spcifications and/or manufacturing procedures.

5. Yes

6. Yes, See response to question 1.


Request Date: 02/29/2016

My questions are directed at MSS SP-75-2014. I am trying to determine the intent of 14.4.8 and 9.1 to establish the required PWHT of welded fittings.

1. Is the longitudinal weld seam required to receive the same normalizing or Q&T heat treatment as the fitting? (i.e., form, weld, PWHT)

2. Is an as-welded longitudinal weld seam permitted on a normalized or Q&T fitting?

3. Is stress relief PWHT permitted on longitudinal weld seams of a normalized or Q&T fitting? (i.e., form, Q&T, weld, stress relief).

Answer Date: 03/21/2016


1. Yes

2. No

3. Yes, for repair welded parts provided they meet 14.5.3. It is also advised that SR 16 be consulted for PWHT after installation.


Request Date: 11/15/2015

In SP-75-2014 there is a new section, 13.6 setting a minimum bore of 93% of the nominal pipe inside diameter. CFR 192 and 195 incorporate by reference the earlier version of SP-75-2008 which does not include this clarification. What is the minimum bore allowable in a SP-75-2008 Fitting? Where is this minimum bore tolerance to be found in the SP-75-2008 document?

Answer Date: 01/20/2016


The minimum bore allowable in MSS SP-75-2008 is not specified.


Request Date: 09/25/2014

1. Does MSS SP-58-2011 address I.D. tolerances for Pipe Straps (Pipe Clips)?

2. If a manufacturer’s tolerance for strap I.D. meets the tolerance shown for corresponding Pipe Clamp I.D., then these straps meet the intent of MSS tolerances?

Answer Date: 05/28/2015


Answer 1.  No

Answer 2.  MSS does not address specific manufacturer’s tolerances. Design tolerances shall be per the individual manufacturer’s drawings and standards.


Request Date: 01/24/2010

What is the standard or remedy recommended by MSS if the pipe fitting marking is not satisfying SP 25? I have a few connection fittings where I can see both weld and punch marks. It looks like it was done at two times. Do we need to scrap these fittings or do we need to re-mark with manufacturer/Third Party presence or do nothing?

Answer Date: 03/29/2010


Answer 1. SP-25, Section 2.4 does not prohibit the use of different marking methods on a given product.


Request Date: 11/11/2009

We have an order of bends, we have run the test bend and want to have it Normalized then the Mechanical Testing done. Our Customer Inspector says that Para 8.3 in conjunction with Para 8.5 requires that the Test Bend be Normalized in the same furnace, and at the same time that we will Normalize the Production bends. Our interpretation of the Para 8.3/8.5 is that the Test Bend can be done in a furnace meeting the requirements set forth in Para 8.5, i.e..... calibration, 50 Deg F range of control etc.. Then when the mechanical testing is done and approved, the lot of bends can be made and then Normalized in A furnace (not necessarily the same furnace) again meeting the requirement set forth in Par 8.5 and following the same Heat Treat Procedure that was used on the Test Bend. We feel he is looking at Para 8.3 and applying the statement "and which has been heat treated in a lot with any of the fittings it represents" to the test bend. Our understanding of this paragraph is that there are two options in Para 8.3: 1) Test specimens shall be taken from the fitting after final Heat treatment. 2) OR from a piece of pipe or plate of the same nominal thickness, same heat of steel from which the fitting is made, and which has been heat treated in a lot with any of the fittings it represents.

Answer Date: 01/13/2010


1.Question: Does a "test bend" constitute "any of the fittings in a lot which it represent" as required in paragraph 8.3 of MSS SP-75?

Answer: MSS SP-75 does not address "test bend", therefore the status becomes a contractual one between the parties involved.

2. Question: If a test bend is normalized in a controlled furnace per paragraph 8.5 does that normalization fulfill the requirements of paragraph 8.3?

Answer: No  See question number 1.

3. Question: If a lot as defined as in paragraph 8.5 is normalized requires more than one furnace load or more than one furnace, will a specimen be required for each separate furnace load?

Answer: Paragraph 9.1.2 requires that any differences in furnace or load size be accounted for to achieve uniform temperature throughout the mass of the load in order to determine the number of representative specimens. Proof of this is most readily established by a specimen from each furnace or load size.


Request Date: 11/17/2009

Sections 1 and 2 set out the Scope and General Marking Requirements for a standard marking system.

Assume that a flange has been marked by the manufacturer with the information required by the relevant ASME standard, but those markings were applied to bare metal using a light stamp. Those markings are then rendered invisible by painting of the flanges and associated pipe work. Does the flange still comply with MSS SP-25 after application of the paint?

Is the answer to this question affected by whether or not the flange marking was inspected and approved by an independent inspector before the paint was applied?

Answer Date: 12/08/2009


Irregardless of independent inspection, if the product was initially marked in accordance with SP-25, it is still in compliance after painting.


Request Date: 10/08/2008

ASTM A403 Standard for Wrought Stainless fitting calls the MSS SP-25 marking requirement. The MSS SP-25 explicitly requires fittings be marked with "... numerals, letter, or symbols cast, forged, stamped, or otherwise made integral with the product..." there do not appear to be exemptions allowing the use of laser, ink, or paint marking. Are there any official interpretations of the MSS SP-25 that would allow use of the non-integral markings?

Answer Date: 10/27/2008


The term "integral" in Section 2.2 of SP-25-1998 does not prohibit the otherwise suitable marking methods described in ASTM A403.

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February 18, 2019

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