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Thread: Impact test requirement

  1. #1

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    Arrow Impact test requirement

    Hi freinds,

    I am working on Pressure vessel column and I have encountered following problem, I mean when I run the program in PV elite following MDMT requirement come i.e. Impact test is not required.


    Required Minimum Design Metal Temperature 10 C
    Warmest Computed Minimum Design Metal Temperature -26 C


    but when i run the program after fixing all the nozzles and i found following MDMT requirement i.e.


    Required Minimum Design Metal Temperature 10 C
    Warmest Computed Minimum Design Metal Temperature 9 C

    It means now impact test is required. so please let me know whether impact test is required for entire plate material or only nozzle material is required?

    Please advise me asap.

    thanking you in anticipation,

    Sam

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    smeercnn
    Hello
    Does this have to do the bonus , you have in UCS -66 ???
    I mean , for example with a cylindrical shell , the selected thickness is bigger than required thickness than Test temperature may be reduced by an amount given in curve UC-66
    see attachement
    Attached Files Attached Files

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    Quote Originally Posted by sameercnn View Post
    Hi freinds,

    I am working on Pressure vessel column and I have encountered following problem, I mean when I run the program in PV elite following MDMT requirement come i.e. Impact test is not required.


    Required Minimum Design Metal Temperature 10 C
    Warmest Computed Minimum Design Metal Temperature -26 C


    but when i run the program after fixing all the nozzles and i found following MDMT requirement i.e.


    Required Minimum Design Metal Temperature 10 C
    Warmest Computed Minimum Design Metal Temperature 9 C

    It means now impact test is required. so please let me know whether impact test is required for entire plate material or only nozzle material is required?

    Please advise me asap.

    thanking you in anticipation,

    Sam
    hello,


    Refer to 2007 ASME BPVC SECT VIII DIV. 2 add. 2008a

    sect 3.11.2.2 Required Impact Testing Based On the MDMT, Thickness, and Yield Strength
    a) If the governing thickness (see paragraph 3.11.2.3.b) at any welded joint or of any non-welded part exceeds 100 mm (4 in.) and the MDMT is colder than 32°C (90°F), then impact testing is required.
    b) Unless specifically exempted in Figure 3.7 for parts not subject to PWHT or Figure 3.8 for parts subject to PWHT and for non-welded parts, materials having a specified minimum yield strength greater than 450 MPa (65 ksi) shall be impact tested.

    3.11.2.3 Exemption from Impact Testing Based On the MDMT, Thickness, and Material Specification
    a) Figure 3.7 for parts not subject to PWHT or Figure 3.8 for parts subject to PWHT shall be used to establish impact testing exemptions based on the impact test exemption curve for the subject material specification and grade or class of the steel, MDMT, and governing thickness of a welded part. If an MDMT and thickness combination for the subject material is on or above the applicable impact test
    exemption curve in Figure 3.7 or Figure 3.8, then impact testing is not required except as required by paragraph 3.11.8 for weld metal and heat affected zones.
    3-24
    b) The governing thickness, g t , of a welded part is determined using the following criteria. Examples of the governing thickness for some typical vessel details are shown in Figures 3.9, 3.10, and 3.11.
    1) For all product forms except castings:
    i) For butt joints except those in flat heads and tubesheets, the nominal thickness of the thickest
    welded joint [see Figure 3.9, sketch (a)],
    ii) For corner, fillet, or lap welded joints, including attachments as defined in paragraph 3.11.1.1,
    the thinner of the two parts joined,
    iii) For flat heads or tubesheets, the larger of paragraph (ii) above or the flat component thickness
    divided by 4.
    2) The governing thickness of a casting shall be its largest nominal thickness.
    3) The governing thickness of flat nonwelded parts, such as bolted flanges, tubesheets, and flat heads, is the flat component thickness divided by 4.
    4) The governing thickness of a nonwelded dished head is the greater of the flat flange thickness divided by 4 or the minimum thickness of the dished portion.
    c) Components such as shells, heads, nozzles, manways, reinforcing pads, stiffening rings, flanges, tubesheets, flat cover plates, backing strips, and attachments that are essential to the structural integrity
    of the vessel when welded to pressure retaining components shall be treated as separate components.
    Each component shall be evaluated for impact test requirements based on its individual material
    classification, governing thickness (see paragraph 3.11.2.3.b), and the MDMT. For welded assemblies
    comprised of more than two components (e.g., nozzle-to-shell joint with reinforcing pad), the governing
    thickness and permissible MDMT of each of the individual welded joints of the assembly shall be
    determined, and the warmest MDMT shall be used as the permissible MDMT of the welded assembly.
    d) Figure 3.7 limits the maximum nominal governing thickness for welded parts not subject to postweld
    heat treatment to 38 mm (1-1/2 in.). Some vessels may have welded non-postweld heat treated
    pressure parts whose thickness exceeds the nominal governing thickness of 38 mm (1-1/2 in.).
    Examples of such welded and non-post heat treated pressure parts are thick tubesheets, flat heads, and
    thick insert plates (with beveled edges) with nozzles or load carrying structural attachments. Such
    welded non-postweld heat treated pressure parts shall be impact tested and shall meet the impact test
    requirements of this Division.
    e) Impact testing is not required for materials with a thickness of 2.5 mm (0.099 in.) and thinner, but such
    exempted materials shall not be used at design metal temperatures colder than -48°C (-55°F). For
    components made from DN 100 (NPS 4) pipe or smaller and for equivalent size of tubes of P-No. 1
    materials, the following exemptions from impact testing are also permitted as a function of the specified
    minimum yield strength (SMYS) of the material for metal temperatures of -104°C (-155°F) and warmer:
    1) For SMYS between 140 - 240 MPa (20 -35 ksi), inclusive, the thickness exemption for impact
    testing is 6 mm (1/4 in.).
    2) For SMYS between 250 - 310 MPa (36-45 ksi), inclusive, the thickness exemption for impact
    testing is 3.2 mm (1/8 in.).
    3) For SMYS higher than 315 MPa (46 ksi), inclusive, the thickness exemption for impact testing is
    2.5 mm ( 0.099 in.).
    f) Note that the rules in this paragraph for the exemption of impact testing do not provide assurance that
    all test results for these materials will satisfy the impact test acceptance criteria of paragraph 3.11.2.1.b.
    3.11.2.4 Exemption from Impact Testing Based On Material Specification and Product Form
    a) Impact testing is not required for the ferritic steel flanges shown below when supplied in heat treated condition (normalized, normalized and tempered, or quenched and tempered) and used at design
    temperatures no colder than -29oC (-20oF) and no colder than -18oC (0oF) when supplied in the as forged condition:
    1) ASME B16.5 flanges,
    2) ASME B16.47 flanges,
    3) Long weld neck flanges, defined as forged nozzles that meet the dimensional requirements of a flanged fitting given in ASME B16.5 but have a straight hub/neck. The neck inside diameter shall not be less than the nominal size of the flange, and the outside diameter of the neck and any nozzle reinforcement shall not exceed the diameter of the hub as specified in ASME 16.5.

    I hope these paragraph will help you,

    Cheers,

    duazo2009
    Last edited by duazo2009; 10-07-2010 at 09:37 PM. Reason: edit

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