ASME Section VIII div 2 2010. ASME Boiler and Pressure Vessel Code. Alternative Rules

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2010 SECTION VIII, DIVISION 2

4-275

Figure 4.13.5 – Some Acceptable Solid Head Attachments to Layered Shell Sections (Continued)

(a) (b)

(c)

(d)

(e)

(f)

Figure 4.13.6 – Some Acceptable Flat Heads and Tubesheets With Hubs Joining Layered Shell

Sections

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Weld Line

(a)

(b)

(c)

(d)

Weld Line

Retaining

Ring

(e-1)

Weld Overlay 15% Bolt Dia. Min.

But Not Less Than 9 mm (0.375 In.)

(e) (f) (f-1)

Retaining

Ring

Weld Line

Optional

(g)

Retaining

Ring

Weld Line

Optional

(g-1)

(e),(e-1),(f),(f-1)(g),(g-1)

Weld Line

Optional

Weld Line

Optional

Tapped

Holes

Notes:

1. The following applies to Sketches (e), (e-1), (f), (f-1), (g), and (g-1): the weld overlay shall tie the overlay,

the overwraps, and layers together, and the bolt circle shall not exceed the outside diameter of the shell.

2. For Sketches (e), (e-1), (f), and (f-1), the angle of the transition and size of the fillet welds are optional,

and the bolt circle shall not exceed the outside diameter of the shell.

Figure 4.13.7 – Some Acceptable Flanges for Layered Shells

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2010 SECTION VIII, DIVISION 2

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0.7 t

min.

3 t

Min.

Taper Line

< 1/2 (t

- t

)

a > 3 Y

60° Min.

Weld Line

(Category B)

(b-1)

Butt Weld Line

(Category A)

(a-2)

(a-1)

3:1 Taper

0.7 t

min.

Detail Of Taper

Figure 4.13.8 – Some Acceptable Layered Head Attachments to Layered Shells

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3:1 Taper Min.

(f) (g) (h)

3:1 Taper Min.

Backing Strip

If Used Shall

Be Removed

(e)

(d)

(c-2)

(a) (b) (c-1)

Section A-A

Smooth Surface

Figure 4.13.9 – Some Acceptable Nozzle Attachments to Layered Shell Sections

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(j)

(i)

0.5 t

min.

C Max.

Inner Shell

C Max.

Solid Hub With

Integral

Reinforcement

Inner Shell

Vent For

Liner

1.25 t

Min. 1.25 t

Min.

C Max.

Integral Nozzle

Reinforcement

Chamfer

1.25 t

Min.

Reinforcing Pad

Full Circumferential

Reinforcement

Layers (Over Wraps)

3 (min.)

(k)

(l)

Notes:

Provide a means, other than by seal welding, to prevent entry of external foreign matter into the annulus

between the layers and the nozzle neck outside diameter for Sketches (i), (j), (k), and (l).

Figure 4.13.9 – Some Acceptable Nozzle Attachments to Layered Shell Sections (Continued)

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Lug Or Ring

(If Necessary)

Support Lug

Or Ring

Hemi-Head

For Other Than Hemi-Heads Special

Consideration Shall Be Given To The

Discontinuity Stress

Support Ring

(If Necessary)

(a)

(b)

I.D.

Support Lug

Or Ring

Support Layer Or

Pad (If Necessary)

I.D.

Lug Or Ring

(If Necessary)

Typ.

Skirt

Tangent Line

Complete Or Partial

Support Band

(If Necessary)

Figure 4.13.10 – Some Acceptable Supports for Layered Vessels

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2010 SECTION VIII, DIVISION 2

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0.3 mm (0.010 in)

(Non-Relevant Gap)

0.3 mm (0.010 in)

(Non-Relevant Gap)

Figure 4.13.11 – Gap Between Vessel Layers

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4.14 Evaluation of Vessels Outside of Tolerance

4.14.1 Shell Tolerances

If agreed to by the user, the assessment procedures in Part 5 or in API 579-1/ASME FFS-1 may be used to

qualify the design of components that have shell tolerances that do not satisfy the fabrication tolerances in

paragraph 4.3.2 and 4.4.4. If API 579-1/ASME FFS-1 is used in the assessment, a Remaining Strength

Factor of 0.95 shall be used in the calculations unless another value is agreed to by the user. However, the

Remaining Strength Factor shall not be less than 0.90. In addition, a fatigue analysis shall be performed in

accordance with API 579-1/ASME FFS-1 as applicable.

4.14.2 Local Thin Areas

4.14.2.1 If agreed to by the user, the assessment procedures in Part 5 or in API 579-1/ASME FFS-1 may

be used to qualify the design of components that have a local thin area. A local thin area (LTA) is a region of

metal loss on the surface of the component that has a thickness that is less than required by paragraphs 4.3

and 4.4, as applicable. If API 579-1/ASME FFS-1 is used in the assessment, a Remaining Strength Factor of

0.98 shall be used in the calculations unless another value is agreed to by the user. However, the Remaining

Strength Factor shall not be less than 0.90. In addition, a fatigue analysis shall be performed in accordance

with API 579-1/ASME FFS-1 as applicable.

4.14.2.2 The transition between the LTA and the thicker surface shall be made with a taper length not less

than three times the LTA depth. The minimum bottom blend radius shall be equal to or greater than two

times the LTA depth (see Figure 4.14.1)

4.14.3 Marking and Reports

The Manufacturer shall maintain records of all calculations including the location and extent of the fabrication

tolerances outside the prescribed limits and/or LTAs that are evaluated using paragraph 4.14. This

information shall be provided to the user if requested and shall be included in the Manufacturer’s Design

Report.

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4.14.4 Figures

Figure 4.14.1 – LTA Blend Radius Requirements

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4.15 Design Rules for Supports and Attachments

4.15.1 Scope

The rules in paragraph 4.15 cover requirements for the design of structural support system(s) for vessels.

The structural support system may be, but not limited to, saddles for a horizontal vessel, a skirt for a vertical

vessel, or lug and leg type supports for either of these vessel configurations.

4.15.2 Design of Supports

4.15.2.1 Vessels shall be supported for all specified design conditions. The design conditions including

load and load case combinations defined in paragraph 4.1.5.3 shall be considered in the design of all vessel

supports.

4.15.2.2 Unless otherwise defined in this paragraph, if a stress analysis of the vessel and support

attachment configuration is performed, the stress results in the vessel and in the support within the scope of

this Division shall satisfy the acceptance criteria in Part 5.

4.15.2.3 The vessel support attachment shall be subject to the fatigue screening criteria of paragraph

5.5.2. In this evaluation, supports welded to the vessel may be considered as integral attachments.

4.15.2.4 All supports shall be designed to prevent excessive localized stresses due to deformations

produced by the internal pressure or to thermal gradients in the vessel and support system.

4.15.2.5 Vessel support systems composed of structural steel shapes shall be designed in accordance

with a recognized code or standard that cover structural design (e.g. Specification for Structural Steel

Buildings

published by the American Institute of Steel Construction). If the support is at a temperature above

ambient due to vessel operation and the recognized code or standard does not provide allowable stresses at

temperatures above ambient conditions, then the allowable stress, yield strength, and ultimate tensile

strength, as applicable, shall be determined from Annex 3.A and Annex 3.D using a material with a similar

minimum specified yield strength and ultimate tensile strength.

4.15.2.6 Attachment welds for structural supports shall be in accordance with paragraph 4.2.

4.15.2.7 Reinforcing plates and saddles attached to the outside of a vessel shall be provided with at least

one vent hole that may be tapped for a preliminary compressed air and soap solution (or equivalent) test for

tightness of welds that seal the edge of the reinforcing plates and saddles. These vent holes may be left

open or may be plugged when the vessel is in service. If the holes are plugged, the plugging material used

shall not be capable of sustaining pressure between the reinforcing plate and the vessel wall. Vent holes

shall not be plugged during heat treatment.

4.15.2.8 If nonpressure parts such as support lugs, brackets, leg supports and saddles extend over

pressure retaining welds, then these welds shall be ground flush for the portion of weld that is covered, or the

nonpressure parts shall be notched or coped to clear these welds.

4.15.3 Saddle Supports for Horizontal Vessels

4.15.3.1 Application of Rules

a) Design Method – The design method in this paragraph is based on an analysis of the longitudinal

stresses exerted within the cylindrical shell by the overall bending of the vessel, considered as a beam

on two single supports, the shear stresses generated by the transmission of the loads on the supports,

and the circumferential stresses within the cylindrical shell, the head shear and additional tensile stress

in the head, and the possible stiffening rings of this shell, by this transmission of the loads on the

supports. The stress calculation method is based on linear elastic mechanics and covers modes of

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