ASME V Flashcards
Weld Joint Categories are….
Category is defined as the location of a weld joint in a vessel, but not a type of join
Category A:
These are Longitudinal, and spiral welded joints within the main shell, and circumferential welds connecting hemispherical heads to the main shell.
Category B:
These are circumferential welded joints within the main shell, and circumferential welds connecting formed heads besides hemispherical to main shells.
Category C:
These are welded joints connecting flanges to nozzles or shell components, and any welded joint connecting one side plate to another side plate of flat-sided vessel.
Category D:
These are welded joints connecting nozzles to main shells, heads, or flat-sided vessels.
Purpose of Categories is to understand
the joint efficiency to use for a weld, and the extent of NDE required.
The tensile strength of the weld should equal or exceed that of the ________ metals to be joined
base
When base metals of different strengths are to be joined by welding, the tensile strength of the weld metal should equal or exceed that of the ____of the two base metals.
weaker
When is full RT needed?
- lethal substances on all butt welds in SHELL/HEAD
2. all butt welds in SHELL/HEAD >1.5” or based on thickness / material
When is full RT needed?
- lethal substances on all butt welds in SHELL/HEAD
- all butt welds in SHELL/HEAD >1.5” or based on thickness / material
- unfired steam boilers
What is spot radiography needed?
- is when the vessel is not in lethal service, and the welded joint is not examined 100%
When is full RT needed? (RT1)
- lethal substances on all butt welds in SHELL/HEAD
- all butt welds in SHELL/HEAD >1.5” or based on thickness / material
- unfired steam boilers
What is spot radiography needed? (RT3)
- is when the vessel is not in lethal service, and the welded joint is not examined 100%
What is spot radiography needed? (RT3)
- is when the vessel is not in lethal service, and the welded joint is not examined 100%. A 50 ft (15 m) increments of the weld, for example, is represented by one spot examination.
RT2?
- vessel is not used for lethal substances, the code allows full RT to be performed on all longitudinal joints (Category A & D),
AND - spot RT performed on circumferential joints (Category B & C).
No Radiography RT4
required for vessels or vessel parts designed for external pressure, or if it won’t be used for lethal substances.
Joint efficiency E is a measure of the (2)
- quality of a weld joint, or
2. how closely the weld approaches the strength of seamless material.
stress calculation for a seamless vessel (no longitudinal weld) or the thickness of seamless heads with a Type 1 circumferential weld, only two conditions apply:
E = 1 if Spot RT is performed on the circumferential weld. E = 0.85 if No RT is performed on the circumferential weld
List the static head/pressure conversion factor
0.433 psi/ft)
List the static head/pressure conversion factor
0.433 psi/ft)
Rules for the design of shells and tubes under external pressure given in this Division are limited to cylindrical shells, with or without (3)
stiffening rings, tubes, and spherical shells.
CUI susceptible range for CS/SS/duplex
a) 10 °F (–12 °C) and 350 °F (177 °C) for carbon and low alloy steels,
b) 140 °F (60 °C) and 350 °F (177 °C) for austenitic stainless steels,
c) 280 °F (138 °C) and 350 °F (177 °C) for duplex stainless steels.
Inspection for CUI shall be considered for (3)
- externally insulated vessels and
- those that are in intermittent service
- operate at temperatures
On vessels, the most susceptible areas for CUI (7)
a) above insulation or stiffening rings;
b) nozzles and manways;
c) other penetrations (e.g. ladder clips, pipe supports);
d) damaged insulation with areas of potential water ingress;
e) areas with failed insulation caulking;
f) top and bottom heads;
g) other areas that tend to trap water.
Considerations on the need for insulation removal are not limited to but include: (8)
a) consequences of CUI leakage;
b) history of CUI for the vessel or comparable equipment;
c) visual condition of the external covering and insulation;
d) evidence of fluid leakage (e.g. stains);
e) equipment in intermittent service;
f) condition/age of the vessel coating under insulation, if applicable;
g) potential for the type of insulation to absorb/hold more water (e.g. calcium silicate versus cellular glass);
h) ability to apply specialized NDE that can effectively locate CUI without insulation removal.
the minimum thickness at a CML can be located by
ultrasonic measurements or radiography.
when localized corrosion is expected or a
concern, it is important that examinations are conducted using
scanning methods such as profile radiography, scanning ultrasonic techniques, and/or other suitable NDE techniques that will reveal the scope and extent of localized corrosion.
Ultrasonic scanning or radiographic profile techniques are preferred where corrosion (2)
is localized or the
remaining thickness is approaching the required thickness.
When a code hydrostatic pressure test is required, the minimum test pressure should be in accordance with the rules of the applicable code
Test Pressure in psig (MPa) = 1.5 MAWP × (Stest temp/Sdesign temp), prior to 1999 addendum
Test Pressure in psig (MPa) = 1.3 MAWP × (Stest temp/Sdesign temp), 1999 addendum and later
When a noncode related pressure test (leak/tightness test) is performed after repairs, the test pressure may
be conducted at pressures determined
by the owner/user.
A close visual inspection of pressure vessel components should not be performed until the vessel pressure is
at or below the MAWP.
To minimize the risk of brittle fracture during a pressure test, the metal temperature should be maintained at
least 30 °F (17 °C) above the MDMT or MAT for vessels that are more than 2 in. (5 cm) thick and
10 °F (6 °C) above the MDMT or MAT for vessels that have a thickness of 2 in. (5 cm) or less.
pressure test temp should not exceed?
120F
During repairs or alterations of pressure vessels, the inspector shall verify that all new materials
(including carbon steel as well as all alloys) are in compliance with the specifications
Crack-like flaws and environmental cracking shall be assessed by an
engineer and/or corrosion specialist.
Substituting NDE procedures for a pressure test after an alteration or major repair may be done only after the
engineer and inspector have approved.
preferential weld corrosion should be accessed
inspector
If the service conditions of a vessel are changed the inspection intervals shall be
established for the new service conditions.
f both the ownership and the location of a vessel are changed, the vessel shall be
internally and externally
inspected before it is reused.
External inspection intervals for vessels in noncontinuous service are the
same as for vessels in continuous service because the external environment does not change during noncontinuous service.
for pressure vessels that are in noncontinuous service, the interval is based on the number of years of
actual service (vessel in operation) instead of calendar years
