2010seac fall seminar welding white.ppt - · pdf fileif a joint penetration weld is ... 2g:...

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Schedule:Schedule:

7:30-8:15 : Breakfast8:15-8:30 : Introduction8:30-9:30 : Masonry Veneer and Cladding Systems9:30-9:45 : Break9:45-10:45 : Welding Knowledge for Structural Engineers10:45-11:00 : Break11:00-12:00 : Post-Tensioned Slab Foundations in Colorado

Gold Sponsor:p

Silver Sponsor: Bronze Sponsor:

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Welding Knowledge for Structural Engineers:

• David Weaver Project ManagerZimmerman Metals, Inc.

Zi

• Curtis Mayes, P.E.Director Preplanning / EngineeringLPR Construction

ZimmermanMetals, Inc.

Introduction to Shop Welding for Structural Engineers

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What is Arc Welding?

Lincoln Electric

Arc welding is using an electric arc to melt a base metal and a consumable such that they fuse together as they cool.

Lincoln Electric

Shielded Metal Arc Welding

SMAW (stick)•Most basic

•Slow due to downtime replacing consumables

•Not common for shop weldingp g

•Common for field welding where a small amount of weld is placed.

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“Wire Feed”

Flux Core Arc Welding (FCAW)

•With and without gas shielding

•With gas shielding is very common in shop settings.

•Without gas is very common in the field at larger welds.

Gas Metal Arc Welding (GMAW)

•Solid wire with gas shielding

Submerged Arc Welding

SAW

M t t d •More automated process

•Multiple wires feed into the welding zone

•Good for large, long welds

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Weld Access

45˚ angle

Account for Mill Tolerances

Flange reinforcing plate

PJP at column flange. Per the book the flange is 5/16” thick, but may

actually be 1/4” thick.

Flange cover plates. Plate on the left has no adjustment for mill

tolerances. Plate on the right could if it is oversized enough. Column baseplate or

cap plate.

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Welding Causes Distortion

Thermal Distortion

•The welded zone shrinks as it cools.• Double sided welds are better then single sided.

• Heat from welding can release residual stresses within the base material.

Welding Causes Distortion

Example: Flange Extension Plates

•The upper detail may result in a “pretzel”.

•The lower detail will have less distortion.

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Fillet vs. PJP vs. CJPTypically, fillet welds 3/4” or less are more economical then PJP or CJP welds of then PJP or CJP welds of similar effective throat.

PJP welds are more expensive then fillet welds due to man hours to bevel the surfaces.

CJP welds are the most expensive due to beveling the surfaces, back gouging, and inspection.

Thick Material needs to be preheated ($$$)

1/8” thru 3/4” requires no preheat.

Over ¾” thru 1 ½” ‐ preheat to 50˚

Over 1 ½” thru 2 ½” ‐ preheat to 150˚

Over 2 ½” ‐ preheat to 225˚

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What does “TYP” really mean?


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All around weld symbol

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All around weld symbol

Bad Better Best

Bad Better

Show PJP Weld Size on Drawings

If a joint penetration weld is shown without a depth then the shown without a depth then the fabricator must assume that it is

a CJP.

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Effective Throat vs. Weld Depth (PJP)The effective throat of PJP welds is dependent upon the welding position upon the welding position and the welding process used.

Therefore, the engineer should show the required effective throat for PJP welds, not the depth of the prep.

Skewed T‐Joints

At skewed T‐joints of less then 80˚ or greater then 100˚ it is best for the engineer to show the effective throat required so the fabricator can choose the most economical weld.

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Inspection ‐ FrequencyIBC Table 1704.3 uses terminology of “continuous” and “periodic”.

Section 1702:

•Continuous‐the full‐time observation of work requiring special inspection by an approved special inspector who is present in the area where the work is being performed.

•Periodic‐the part‐time or intermittent b i f k i i i l observation of work requiring special

inspection by an approved special inspector who is present in the area where the work has been or is being performed and at the completion of the work.

AISC –Chapter N

2010 AISC Manual of Steel Construction will include Chapter N.

Draft copy available at www.aisc.org/chapterN

Uses terminology of “observe” and “perform”.

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Ultrasonic Testing (UT)

Similar to radar.Similar to radar.

Sends out a pulse of high frequency sound and then senses for those waves to bounce off weld discontinuities back towards the sensor.

Ultrasonic Testing (UT)Sensors are commonly available in 4 different preset angles: 70˚, 60˚, 45˚, and 0˚.

Screen shows operator how much 70˚of the pulse bounces back and how far it traveled. Path of

ultrasonic pulse

Location of minorLocation of minor discontinuity in weld

Distance Pulse Traveled

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Magnetic Particle and RadiographicMagnetic Particle

•A magnetic powder is spread across the testing area The area is magnetized

Radiographic

•Essentially X-ray film process.testing area. The area is magnetized, moving the powder into a magnetic field pattern. Proper reading of the pattern can highlight discontinuities or cracks.

•Only detects cracks and discontinuities withing 0.1” of the surface

•Requires access to the back side of testing area to secure testing film or radiation source.


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Introduction to Field Welding for Structural Engineers

Priority #1 Safety

W18x46

y y

W18x46

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1.Original Drawing

W18x462.Column Changed to Precast

W18x46

3.Typical temporary support selected for cantilevered beam.

4.2 A307 bolts used for support, followed by field welded flange

plates and web clip angles.

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Priority #2 Inspect What You Expect

Priority #3Empathy: the action of understanding, being aware

Imagine yourself wearing the Ironworker’s Boots.understanding, being aware

of, being sensitive to, and vicariously experiencing the feelings, thoughts, and experience of another of either the past or present without having the feelings, thoughts and experience

As well as wearing thoughts, and experience

fully communicated in an objectively explicit manner; also : the capacity for this

wearing the face shield.

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Priority #4: Position of the weld:

Initially, We Ironworkers learn how to weld on the ground…

Then, the real world sets in.

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ht S

ide

Up

Rig

hU

p SSide D

ownOK. We still weld on the ground in gthe field,

but…

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AccessAccess

AAccess

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Priority #5: Quantity of the weld:Fillet Weld Size Matters:

Fillets Welds: Production = passes5/16” is typical maximum field weld fillet size and optimum weld size.

Bump a 5/16” weld up to 3/8” and it takes almost twice along to install. Fillet Weld Cost Comparison

Load to Resist

Fillet Weld Size

Strength of Weld

Linear Inches of Weld

Required

Number of Passes Required

Total Inches to weld

Prodiction Inches per

hour

Hours to weld

Cost Per Hour

Cost to weld

$ per kip Relative Cost

100.0 kips 1/8 ” 1.9 k/in 53.9” 1 53.9” 60.0”/hr 0.898hrs $ 55.00 $ 49.38 $ 0.49 150% increase over 5/16" size100.0 kips 3/16” 2.8 k/in 35.9” 1 35.9” 60.0”/hr 0.599hrs $ 55.00 $ 32.92 $ 0.33 67% increase over 5/16" size100.0 kips 1/4 ” 3.7 k/in 26.9” 1 26.9” 60.0”/hr 0.449hrs $ 55.00 $ 24.69 $ 0.25 25% increase over 5/16" size100.0 kips 5/16” 4.6 k/in 21.5” 1 21.5” 60.0”/hr 0.359hrs $ 55.00 $ 19.75 $ 0.20 0% increase over 5/16" size100.0 kips 3/8 ” 5.6 k/in 18.0” 2 35.9” 60.0”/hr 0.599hrs $ 55.00 $ 32.92 $ 0.33 67% increase over 5/16" size100.0 kips 7/16” 6.5 k/in 15.4” 2 30.8” 60.0”/hr 0.513hrs $ 55.00 $ 28.22 $ 0.28 43% increase over 5/16" size100.0 kips 1/2 ” 7.4 k/in 13.5” 3 40.4” 60.0”/hr 0.673hrs $ 55.00 $ 37.04 $ 0.37 88% increase over 5/16" size100.0 kips 9/16” 8.4 k/in 12.0” 4 47.9” 60.0”/hr 0.798hrs $ 55.00 $ 43.90 $ 0.44 122% increase over 5/16" size100.0 kips 5/8 ” 9.3 k/in 10.8” 5 53.9” 60.0”/hr 0.898hrs $ 55.00 $ 49.38 $ 0.49 150% increase over 5/16" size100.0 kips 11/16” 10.2 k/in 9.8” 5 49.0” 60.0”/hr 0.816hrs $ 55.00 $ 44.89 $ 0.45 127% increase over 5/16" size100.0 kips 3/4 ” 11.1 k/in 9.0” 6 53.9” 60.0”/hr 0.898hrs $ 55.00 $ 49.38 $ 0.49 150% increase over 5/16" size100.0 kips 13/16” 12.1 k/in 8.3” 7 58.0” 60.0”/hr 0.967hrs $ 55.00 $ 53.18 $ 0.53 169% increase over 5/16" size100.0 kips 7/8 ” 13.0 k/in 7.7” 8 61.6” 60.0”/hr 1.026hrs $ 55.00 $ 56.44 $ 0.56 186% increase over 5/16" size100.0 kips 15/16” 13.9 k/in 7.2” 10 71.8” 60.0”/hr 1.197hrs $ 55.00 $ 65.84 $ 0.66 233% increase over 5/16" size100.0 kips 1” 14.9 k/in 6.7” 11 74.1” 60.0”/hr 1.235hrs $ 55.00 $ 67.90 $ 0.68 244% increase over 5/16" size

Priority #6: Be Specific

Field Weld flags must be specific and intentional

Specs need to address backup bars, runoff tabs, etc…

How much weld is REALLY required? Don’t need any here? Great!

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Four Basic Welding Positions1G: Plates horizontal, flat weld

2G: Plates vertical, axis of weld horizontal2G: Plates vertical, axis of weld horizontal

3G: Plates vertical, axis of weld vertical

4G: Plates horizontal, overhead weld

Three Basic Welding Joints1. Fillet

2. Partial Penetration

3. Full Penetration

Three Basic Welding Joints

Two Basic Field Welding Processes

1: SMAW for less welding at a single location1: SMAW for less welding at a single location

2: FCAW for more welding at a single location

There are several other processes available for the field, but they are all

rarely used

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Now: Let’s Get to Work

Connection Design

Bolts areBolts are great, but

sometimes weld is better.

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AESS welding?

Get a sample and review from the proper distance. Don’t perfect a

Backer Bars?Leave them on if

you can.

Run-off tabs?Don t perfect a finish that can’t be

seen.

Run off tabs? Leave them on if

you can.

Field welding on galvanized material?

Doesn’t that ruin the corrosion protection? Avoid field welding by

Need to fill a rat hole for p g y

design if possible.

If you must do this, avoid the fumes. E6011 is more forgiving for a less

experienced welder. E7018 is OK as long as the machine settings are

correct.

architectural reasons?

Read about tri-axial stresses, then decide.

OK. This talk Is about welding, but don’t

weld if you don’t need to… OK?

STEEL ERECTORSCONSTRUCTION

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OK. But this is a really tough weld. Is there

another way?


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Priority #1: SafetyPriority #2: Inspect What You Expect

Priority #3: Be Empathetic to the IronworkerPriority #3: Be Empathetic to the IronworkerPriority #4: Position, Position, Position

Priority #5: QuantityPriority #6: Be Specific

P i it #7Priority #7:

Get Plenty of Rest

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Questions?

Welding Knowledge for Structural Engineers:

• David Weaver Project ManagerZimmerman Metals, Inc.

Zi• Curtis Mayes, P.E.

Director Preplanning / EngineeringLPR Construction


2010seac fall seminar welding white.ppt - · pdf fileif a joint penetration weld is ... 2g:...

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