Study Questions Flashcards
How many welds does API 577 require to be RT’d?
None / The # of welds to RT is established by the primary code
Arc Blow
Deflection of an arc from it’s normal path due to magnetic forces
Arc Length
The distance from the tip of the welding electrode to the adjacent surface of the weld pool.
Autogenous weld
A fusion weld made without filler metal
Backing
Material placed at back side of joint to support and retain molten weld metal.
Defect
Discontinuity(s) that render a part or product unable to meet min applicable standards or specs. The term designates rejectability
Discontinuity
An interruption of the typical structure of a material. May or may not be a defect depending on severity.
Inclusion
(SOFT) Entrapped foreign solid material such as Slag, Oxide, Flux, Tungsten (SOFT)
Undercut
A groove melted into the base metal adjacent to the weld toe or weld root and left unfilled by weld metal.
Corrective action of non-conformance:
Based on nature of non-conformance
Which welding process is most widely used
SMAW
Describe the SMAW process
Arc between covered electrode and weld pool. Heat of arc comes from tip of a consumable covered electrode. Shielding comes from decomposition of the electrode coating
Arc Between Electrode & Pool
Heat comes from electrode
Shielding comes from electrode coating
Basic Functions of the SMAW electrode coating
- Shielding Gas
- Prevent excessive grain growth
- Slag blanket to protect weld
- Sometimes provides alloy elements
SHIELD
PEG
BLANKET
ALLOY
Advantages of SMAW
Simple
Suitable for most commonly used metals
Limitations of SMAW
Deposition rates are lower
Advantages of GTAW
Produces high purity welds
Little postweld cleaning
Limitations of GTAW
Low deposition rates
Low tolerance for contaminants
Difficult to shield
Advantages of GMAW
Only consumable that can weld most commercial metals & alloys
High deposition rates
Minimal cleanup
Limitations of GMAW
Complex equipment
Advantages of FCAW
Metallurgical benefits from flux
Higher deposition and productivity rates
Shielding produced at the surface, more tolerant of wind.
Limitations of FCAW
Complex equipment
Requires exhaust equipment
Slag needs to be removed between passes
Backing material required for root pass
Advantages of SAW
Very high deposition rates
High quality welds
Limitations of SAW
Weld is not visible during the welding process
Expensive equipment
Limited to shop applications and flat position
SMAW stands for
Shielded Metal Arc Welding
GMAW stands for
Gas Metal Arc Welding
GTAW stands for
Gas Tungsten Arc Welding
FCAW stands for
Flux Cored Arc Welding
SAW stands for
Submerged Arc Welding
Which GMAW transfer mode is “fast-freezing” and tends to have LOF
GMAW - Short Circuit Mode
Which process uses a directed stream of discrete drops
GMAW - Spray Transfer Mode
Variables required on WPS
Essential, non-essential and supplemental essential when toughness testing is required
Variables required on PQR
Essential, non-essential are optional
Per Section IX, who supervises the testing of a PQR coupon?
Manufacturer or contractor - the owner of the procedure
What are welding materials?
Base metal, filler metal, fluxes & gases
What is the purpose of P-Numbers?
Reduce the # of welding procedure qualifications required
What is the basis for F-Numbers
Usability characteristics
What is the qual limits for a welder who qualifies using an electrode from a specific F-Number family?
Qualified for all electrodes of the same F-Number. With carbon steel, also qualifies for other F-Numbers
What alloy is P-53
Titanium
What is the A-Number
ANALYZE / Analysis of chemical composition of the weld
Where are some electrodes stored
Warm holding ovens
Low Hydrogen electrode storage
Separate from other electrodes
What to do with wet fluxes or electrodes
Discard
Change in WPQ essential variable requires
Welder Requal
Which discontinuity is at the toe of the weld?
Overlap, Undercut is also correct but was not one of the 4 choices
ET is useful NDE method for which type of joints?
Butt welds
How best to find side wall lack of fusion?
UT
What is the most extensively used NDE methods for welds?
Visual
Visual exam distance
6-24”
Visual exam minimum angle
30 degrees
Needed light intensity
100 foot candles
Use of Bridge Cam gauge
Measure weld prep angle
MT - Flux direction best to see a discontinuity
Perpendicular to discontinuity
Result of MT Residual magnetism
Deflect Arc
PT on SS watch out for
Chlorine and fluorine, Code mentions chlorine, sulfur and halogens but fluroine has been a test answer
PT max temp limit
125 F
What determines which IQI should be used
Thickness of base metal plus reinforcement
Placement of Wire IQI
Perpendicular across weld
Typical RT sources
IR 192 and Cobalt 60
Iridium 192 use on what wall thickness
1/4-3”
Cobalt 60 use on what wall thickness
1.5-7”
UT Calibration
Before & After exam
UT calibration block temp
w/in 25F of part to be examined
UT recalibration
at least every 4 hours
Direction of UT angle beam scan for indications transverse to the weld
Parallel to the weld
Why use Hardness Testing
Weld & HAZ, & after PWHT to see if mat’l soft
Use of FMR (Field Metallography Replication)
Find excessively hard HAZ structure
Pressure test typical holding time
at least 30 minutes
Weld metal is similar to that of
Castings
Ductility Definition
The ability of a material to deform plastically without fracturing
Names of hardness tests
Brinell, Rockwell, Knoop & Vickers
What is the heat affected zone (HAZ)
Portion of base metal that has not been melted but whose mechanical properties or microstructure has been altered
For carbon steels, the HAZ is parent metal NOT melted but exceeded what temperature?
1350 F
Define Toughness
Ability of a material to absorb energy and deform plastically before fracturing
One of the most common tests for toughness
Charpy Impact test
What do low toughness values indicate
Brittle material
Primary reason for PWHT
Relive residual stress
Test for hardenability
Jominy Bar
Hardenability is related to the amount of
Martensite formed during heating & cooling
Significant amounts of martensite in the HAZ can lead to
Hydrogen cracking or a loss of Ductility and Toughness
Brinell Hardness limit for 1-1/4 chrome - 1/2 moly
225
Austenitic welds required how much delta ferrite to resist cracking
5-20%
Differences in welding nickel alloys
Tendency to be sluggish
Rod type to use when hot tapping:
Low hydrogen electrodes
Examples of low hydrogen electrodes:
E7016, E7018 & E7048 “7016,18 & 48”
Product flow rate in piping during hot tapping
1.3 - 4.0 ft/sec
Maximum rod size to use when hot tapping material less than 1/4” thick?
3/32” diameter
Marking in the tail of a weld symbol
Specification or Process
Meaning of the first two digits of a SMAW Electrode
Tensile Strength
What processes use a rod with designation “ERXXX”
GMAW/GTAW
What does “S” mean in electrode designation of GMAW/GTAW
Solid Wire
Common SMAW electrode used for root pass on carbon steel welds
E6010
