Lesson 13 wriiting a wps by_essential_new2

API 510 Preparatory ClassAPI 510 Preparatory Class

Lesson 13 Lesson 13

Writing a Welding Procedure Writing a Welding Procedure SpecificationSpecification

SECTION IX

Qualifying A Welding Procedure By Essential Variables

All Referenced Section IX Pages are from the 2001 Edition with Addenda through 03

SECTION IX

When qualifying a welding procedure you must first determine the important properties of the planned weldment which then become the essential variables. The basic ones are:

• Base metal to be welded and thickness (T) required.

• Process (es) to be used including filler metal (s).• Preheat.• Postweld heat treatment or the lack of.• Various others specific to the welding process

used.

For this instruction we will use the SMAW Process. The brief of Essential, Supplementary Essential and Non-Essential Variables for the SMAW process are listed in table QW-253. However this part of the course will only cover Essential Variables not the supplementary or non-essentials. The non-essentials will be covered latter. A definition of these variables follows.

Essential Variable – A variable that if changed requires requalification of the procedure by the welding and testing of a new coupon or support from a previously qualified Procedure Qualification Record (PQR), i.e. a change in the base metal thickness (T) qualified.

Supplementary Essential – An essential variable that is used only when impact testing of a base metal is required by a construction code, i.e. a change from one P-No. Group to another such as P1 Gr.1 to Gr.2.

Non-Essential – A variable that can be changed as needed to suit production requirements without requalification. A change in the groove design, etc.

QW-253 SMAW Brief of Variables Page 21

We will start our discussion with the top half of the SMAW brief of variables, beginning with the first two Essential Variables, Base Metal and Filler

Metal.

QW-253 SMAW Brief of Variables

Notice that each variable references a paragraph in Article 4.

For example under Base Metals we have the entry T/t Limits > 8 inches which is referenced to paragraph QW-403.7 Page 58

Defining Each Essential Variable Base Metals QW-403.7 Pages 21,58 &139

• T/t Limits > 8 inches - this rule only applies at thickness greater than 8 inches (203 mm) .

• Unless you will be welding something over 8 inches this is of little concern. The rule for most welding procedures is the maximum that can be welded is 2 times T (the coupon). If you are welding a coupon over 8 inches you are restricted to 1.33T or 1.33t, as applicable. 1.33t is the weld metal thickness, it matters when mixing welding processes and/or filler metal F-Numbers.

Defining Each Essential Variable Quiz

1. An 8-1/2” T coupon was welded to produce a PQR to support welding of a reactor shell course. The maximum T qualified with this coupon is ___”.


1. An 8.5” T coupon was welded to produce a PQR to support welding of a reactor shell course. The maximum T qualified with this coupon is 11.305”.

8.5 X 1.33 = 11.305

Defining Each Essential Variable Base Metals Pgs. 21, 58,139, &16

• Change in Thickness (T) qualified. • QW-403.8 A change in base metal thickness beyond the

range qualified in QW-451, except as otherwise permitted by QW-202.4(b) (different thickness at the joint)

• Of concern is the thickness range qualified by the supporting PQR (s) for the WPS, from less than a 1/16” to less than 1-1/2” it is 2 x T. To weld a thickness outside the range supported by the PQR the WPS production welding changes must be supported by providing an additional PQR from file or by welding a new PQR test coupon.

Defining Each Essential Variable Base Metals

Quiz

1. A 1”(25mm) to 1”(25mm) P-No.1 coupon was welded entirely by the SMAW process. The minimum thickness qualified is ___ and the maximum is ___”


Quiz

1. A 1”(25mm) to 1”(25mm) P-No.1 coupon was welded entirely by the SMAW process. The minimum thickness qualified is 3/16 ” and the maximum is 2”.


t (weld metal) pass greater than 1/2” Pages 21 & 58

• QW-403.9 For single-pass or multi-pass welding in which any pass (means layer of weld metal) is greater than 1/2 in. (13 mm) thick, an increase in base metal thickness beyond 1.1 times that of the qualification test coupon.

• The thickness range is affected. It will be restricted to 1.1 T as given above if you deposit more than 1/2” of weld metal in a single pass (layer). This has to do with heat input.

Defining Each Essential Variable A single pass refers to the number of weld beads required to fill up a layer of weld metal in the joint. If the single layer/pass, t (deposited weld metal), exceeds 1/2” in thickness the WPS will be restricted to 1.1 x T in production welding.


A PQR coupon is 1-1/4”(1.250) thick (T). The weld will be made in three passes, the root pass/layer will be 1/4” (.250) thick and second and third layers/passes will be each be 1/2”(.500) thick. The maximum range of thickness for this qualification will be ________”.


A PQR coupon is 1-1/4”(1.250) thick (T). The weld will be made in three passes, the root pass/layer will be 1/4” (.250) thick and second and third layers/passes will be each be 1/2”(.500) thick. The maximum range of thickness for this qualification will be 2-1/2 (2.500)”.

Read closely, the rule states it must exceed 1/2” to be limited to 1.1 x T.

Defining Each Essential Variable Alternate Base Metals for Procedures

• QW-403.11 Pages 21 & 58 • Base metals specified in the WPS shall be

qualified by a procedure qualification test which was made using base metals in accordance with QW-424.

QW 424 – Turn to Page 131Base Metal (s) Used for Procedure Qualification Test Coupon Versus

Base Metal Qualified for production

Let’s examine some of the items in the table.

One Metal From A P-No. To Any Metal From The Same P-No. such as P1 to P1 which qualifies all P1 metals, i.e. pipe and/or plate.

One metal from a P-No. To any metal from any Other P-No. We will Use P-No.1 to P- No.8 as an example. Other combinations are possible, P Nos. 1 to 3, P Nos.3 to 4 etc.

One metal from P-No. 3 To anyother metal from P-No. 3

One metal from P No. 3 to anyother metal from P No. 3

Also qualifies P No. 3 to P No. 1

However one metal from P No. 3 to anymetal from P No. 3 does not qualify P No. 1 to P No. 1

One metal from P-No. 4 to anyother metal from P-No. 4

One metal from P No.4 to any other metal from P No.4 also qualifies P No.4 to 4, 3 and, 1.

It qualifies one metal from P No. 4 to anymetal from P No. 4, 3 or 1. but does not qualify P No. 3 to P No. 3 or P No. 1 to P No.1

Quiz

Using the table list the base metals qualified if we successfully weld a procedure coupon joining P-No. 5A to P-No. 5A

Quiz # 1 – P-No. 5A to P-No. 5A Qualifies?

P-No. 5A to __, __,__, or __. It does not qualify __, __, or __ to each other or to their selves.

P-No. 5A to P-No. 5A Qualifies?

P-No. 5A to 5A, 4, 3, or 1. It does not qualify 4 , 3, or 1 to each other or to their selves.

Quiz # 2 P-No. 5A to P-No. 4, 3, or 1 Qualifies?

P-No. 5A to any metal assigned __,__, or __. It does not qualify __, __, or __ to each other or to their selves.

Quiz # 2 P-No. 5A to P-No. 4, 3, or 1 Qualifies?

P-No. 5A to any metal assigned 4,3, or 1. It does not qualify 4, 3, or 1 to each other or to their selves.

Defining Each Essential Variable Base Metals Pages 21 & 58

• Change of P-No. 5/9/10• QW-403.13 A change from one P No. 5 to any

other P-No. 5 (P-No. 5A to P-No. 5B or P-No. 5C or vice versa). A change from P-No. 9A to P-No. 9B but, not vice versa. A change from one P- No.10 to any other P-No.10 (P-No.10A to P- No.10B or P-No.10C, etc., or vice versa).

• Simple, P-No. 5/9/10 - A,B,C.., are different P-Numbers and will require individual qualifications, (with the exception of going from 9B to 9A)

Defining Each Essential Variable Filler Metals

• Change of F-Number Pages 21 & 59• QW-404.4 A change from one F-Number in QW-

432 to any other F-Number or to any other filler metal not listed in QW-432.

• Changing the F-Number on the WPS to one other than that used for the procedure test coupon (PQR). Such as changing from F-No. 1 to F-No. 3.

• This rule also applies to a welder’s qualification test by the way.


• QW- 404.5 Change of A-Number Pages 21,59 & 138

• A-Nos. are the chemical analysis’ of the ferrous weld metal deposits produced by a given filler metal. Changing A numbers can change the chemistry and possibly the mechanical properties of the weldment. It also changes the weld add mixture, that part that contains both base metal and weld metal. This occurs when changing filler metals. Changing the A No. to one other than that used to qualify requires a new test or additional PQR (s) from a file (with one exception).

And we find the following rule, proving you must read Section IX completely!

• QW-404.5 (Applicable only to ferrous metals.) A change in the chemical composition of the weld deposit from one A-Number to any other A-Number in QW- 442.

Qualification with A-No. 1 shall qualify for A-No. 2 and vice versa. (Note: all other A- No. changes will force requalification).

The dot dot dot in table below indicates not specified to be present, single values are maximums. i.e. Carbon is limited to 0.20 % maximum for A-No.1

Filler Metals

Consider the following filler metals for the SMAW process.

1. E-7018 which has an A-Number of 1.

2. E-7018A1 which has an A-Number of 2.

Compare the chemistry tables of the IX A–No.s to Section II Part C Filler Metals and to a Hobart filler metal manufacturer Data Sheet.

From Section IX QW-442 A No. 1 by Max. %

C 0.20/ Cr…/ Mo…/ Ni…/ Mn 1.60/ Si 1.00

From Section II Part C / E-7018 SFA 5.1

A No. 1 contains by %

C 0.20/ Cr…/ Mo…/ Ni…/ Mn 1.60/ Si 1.00

Hobart’s Data Sheet for E-7018

Comparing All Three for E-7018

C 0.20

A-No. 1Section IX

Cr --- Mo --- Ni --- Mn 1.60

Si 1.00

C …

SFA- 5.1Sect. II C

Cr 0.20 Mo 0.30 Ni 0.30 Mn 1.60

Si 0.75

C 0.07Hobart

Data

Cr .043 Mo .009 Ni .019 Mn 0.88

Si 0.37

From the Section IX QW-442 A No. 2 by Max. %

C 0.15 / Cr 0.50/ Mo 0.40 – 0.65/ Ni…/ Mn 1.60/ Si 1.00

From Section II Part C / E-7018A1 SFA 5.5

A No. 2 contains by Max %

C 0.15 / Cr 0.50/ Mo 0.40 – 0.65/ Ni…/ Mn 1.60/ Si 1.00

Hobart’s Data Sheet for E-7018A1

Comparing All Three for E-7018A1

C 0.15

A-No. 2 Section IX

Cr 0.50 Mo

0.40-0.65

Ni… Mn 1.60

Si 1.00

C 0.12

SFA- 5.5 Sect. II C

Cr… Mo

0.40-0.65

Ni… Mn 0.90

Si 0.80

C 0.04Hobart

Data

Cr… Mo 0.43 Ni… Mn 0.81

Si 0.44

A note on the API Exams

• If you are taking any of the three API Exams you will be required to review a WPS and PQR. Part of that review might be a question about the A-Number listed for the filler metal in the documents. This is a protest question. You would need ASME Section II Part C to answer that question. Sect. II Part C is not listed as required for the exam. You have no way of answering!


• Change in the deposited t, Pages 21 & 61• QW-404.30 A change in deposited weld metal

thickness beyond the range qualified in QW-451 for procedure qualification.

• Example: In a SMAW procedure 1/4” of E-6010 was qualified on the PQR by depositing 1/8” in the coupon (2t), the balance of the coupon was filled with E 7018. The need arises to increase the E-6010 weld metal t to 3/8” in production. This would require a new coupon or an existing PQR.

Defining Each Essential Variable

Preheat - Turn to Page 21

Defining Each Essential Variable Preheat - Pages 21 & 62

• A decrease in preheat greater than 100o F

• QW-406.1 A decrease of more than 100°F (38°C) in the preheat temperature qualified. The minimum temperature for welding shall be as specified in the WPS.

• Example: A PQR coupon was welded using a preheat of 250°F (121°C) but the WPS requires a preheat of only 100°F (38°C). This is a 150°F (66°C) decrease below that qualified and will require a new PQR or one from your files to support the lower temperature.

Defining Each Essential Variable PWHT

• Change in PWHT Pages 21 & 62

• QW-407.1 This long paragraph specifies what is considered a change in post weld heat treatments. The changes are P-Number specific with 5 different conditions of PWHT for P Nos. 1,3, 4, 5, 6, 9,10 and, 11.

For most of those and all other materials there are two conditions:

1. No PHWT

2. The specified PWHT for the P No. used based on a construction Code.

Defining Each Essential Variable PWHT

• T Limits (Thickness Limits) Pages 21 & 63• QW-407.4 For a procedure qualification test

coupon receiving a post weld heat treatment in which the upper transformation temperature is exceeded, the maximum qualified thickness for production welds is 1.1 times the thickness of the test coupon.

• This rule only applies when a production weld will undergo heat treatment at temperature that will alter the base metal’s physical properties, such as normalizing, etc.

Producing The PQR

We have looked at all of the essential variables for the SMAW process. Let’s put it all together by filling out a SMAW PQR to support a Welding Procedure Specification (WPS). To do this it will be necessary to specify a list of the essential variables for the welding we have planned.

Producing The PQR

From QW-253 we need to address the basic essential variables and the ranges to be used:

1. Base Metal (s) – 2” SA-516 Gr. 70 P-No. 1

2. Filler Metal (s) – E-7018 Only

3. Preheat – 175 o F for P-No.1 (from Sect. VIII Div. 1 non-mandatory Appendix R)

4. PWHT – 1100 o F Minimum per inch of thickness for P-No. 1 (from Sect. VIII Div. 1 UCS-56)

First we will fill out the top half of the PQR from the company name to the base metal information on the left side and include a graphic of the joint design used to weld the coupon.

Next we will fill out the bottom half of the PQR with the filler metal and preheat on the left side. While not required on the PQR by Section IX the Non-Essential variables will be entered as well.

Now we will fill out the upper half of the PQR with the PWHT metal on the right side. Making the comment Not Applicable in the box for Gas, since the SMAW process does not use shielding gasses.

Finally the bottom right which consists of all non-essential variables. Once again these are not required by Section IX, but may be helpful for meeting a construction code requirement, i.e. Section VIII Div. 1 or B31.3.

Now we start completing the back of the PQR. To do so we need some test results for our required tension and bend tests. The tension test specimens are fabricated as given in Section IX QW-462.1(a). Page 152 .

The required number of tension test specimens are 2 as shown in Section IX QW-451.1 Page 139. The required number of tension specimens are always two, when your coupon exceeds 1”, you are allowed divide the two specimens into multiple pieces. (see QW-151.1 (c) and (d) )

The ultimate strength of the tension specimens must be computed as described in below in QW-152.

• QW-152 Tension Test Procedure

The tension test specimen shall be ruptured under tensile load. The tensile strength shall be computed by dividing the ultimate total load by the least cross sectional area of the specimen as calculated from actual measurements made before the load is applied.

We must measure each specimen’s width and thickness after machining as shown in QW-462.1(a). Section IX requires two specimens be tested.

The data for our specimens was;

TS1 - width = .750” thickness = .453”

TS2 - width = .753” thickness = .456”

Area for each specimen.

TS1= .750 x.453 = .340 in.2

TS2= .753 x.456 = .343 in.2

We put the specimens in a tensile tester and pull each one apart;

The specimens were broke in the tensile tester and the breaking forces as read from the gage on the machine were recorded as follows ;

TS1 = 25,010 Lbs.

TS2 = 24,050 Lbs.

Computing the ultimate strength for 1 square inch for each specimen;

‘Load divided by Area’

25,010/.340 = 73,558 PSI

24,050/.343 = 70,116 PSI

We now evaluate the specimens;

‘Load divided by Area’

25,010/.340 = 73,558 PSI

24,050/.343 = 70,116 PSI

Observing the character and location of the specimen failures, it was noted that both failed in the base metal outside of the weld heat affected zones and in a ductile manner.

We can now record this information on the back side of the our Procedure Qualification Record.

‘But First’

We must determine the required minimum specified strength from Section IX in the P-Number listings.

Turn to Page 96 of Section IX

We find that SA-516 Grade 70 has a Minimum Specified Tensile Strength of:

70 KSI = 70,000 Pounds Per Square Inch.

Our tensile specimens exceeded the minimum. Now we have one more task to complete. We must do 4 side bend tests. This requirement is found in Section IX along with the accept/reject values for all bend tests. Turn now to Page 139 again.

The required type and number of bend tests based on a 1” thick coupon are 4 Side Bend tests. Side bends are mandatory after the coupon thickness reaches 3/4” or larger.

We must evaluate the bend specimens to section IX QW-163. Turn now to Page 6.

QW-163 - The guided-bend specimens shall have no open discontinuity in the weld or heat-affected zone exceeding 1/8 in. (3.2 mm), measured in any direction on the convex surface of the specimen after bending. Open discontinuities….etc.

To see the details for making the bend specimens look at QW-462.2 Page 156.

We evaluated the bend specimens to section IX and had the following comments.

Side Bend S1. No open defects acceptable

Side Bend S2. 1/32” acceptable



We have the correct type based on the coupon thickness and the correct number of acceptable side bend tests.

We can now fill out the top back of the PQR.

All that is left is to fill out the bottom of the back of the PQR. This will be easy, just a few housekeeping items to complete.

Here is the front side of the complete Procedure Qualification Record

Here is the back side of the complete Procedure Qualification Record

The WPS

• We have completed the Procedure Qualification Record, which is a laboratory report of the welding and testing of a coupon.

• From this PQR we will write a Welding Procedure Specification. It must be in complete agreement concerning Essential Variables with the PQR.

The WPS• The Welding Procedure Specification, must be

complete. You must address all of the essential, supplementary essential (if Notch toughness testing is required), and non-essential variables. The best approach is to use of the Brief of Variables found in QW-253 on Page 21 as an item check list.

• We will go line by line and address all of the Essential and Non-Essential variables only and since our WPS will not require toughness testing, Supplementary Essentials will be omitted.

The WPS

Starting in box QW-402 we will address each of the non-essential variables.

• Groove Design• Backing• Root Spacing• Retainers

The following is how it was completed.

The WPS

In box QW-402 we have addressed each of the non-essential variables as follows;

• Groove Design – Single Vee, Double Vee, J-Groove and, U-Groove

• Backing – The X in both the Yes and No boxes denotes that this WPS may be used with or without backing.

• Root Spacing –This is given below Details.• Retainers – Also given below Details.

The WPS

Since we have addressed each of the non-essential variables and thereby giving all the needed Joint information for making a weldment.

It is complete for joint design and no one should have to ask what is allowed when using this WPS. Notice that BWC-112A is referenced for the actual details of the various joints, such as included angle of Vee grooves and depths of J and U grooves.

The WPS

Next QW-403 Base Metals

The WPS

We have addressed each of the essential variables under Base Metal QW-403.

It is complete for P-No., Thickness range and the restriction of No t Pass > 1/2” has been addressed. Supplementary Essentials need not be addressed, since no impact testing is required of this weldment.

The WPS

Next QW-403 Filler Metals

The WPS

We have addressed each of the essential variables under Filler Metal QW-404.

It is complete for AWS Classification, F-No., A-No., Size of Filler Metals, and Weld Metal Thickness Range and all essential variable entries are correct.

The WPS

Next the back and top of the WPS

We will now complete the Positions, Preheat, Electrical, and Postweld Heat Treatment on the WPS.

The WPS

1. The Positions for use with this WPS are, Flat, Horizontal, Vertical and, Overhead. This instructs that this WPS can be used with all positions.

2. The Preheat minimum is set at 100oF(38oC) which is within 100oF of the PQR actual value of 175oF.

3. The Preheat Maintenance specified as none required.

The WPS

The Electrical Characteristics are;

1. Direct Current Electrode Positive.

2. Amps (I) are set to a range of 90-190 and the Volts (E) are set to a range of 15-25, these values are normally obtained from the filler metal manufacturer’s literature or from actual experience.

3. The rest are not required for SMAW.

The WPS

The Postweld Heat Treatment values are:

1. 1150 +/- 50oF (621+/- 10oC) Which is in agreement with the PQR minimum value of 1100oF (593oC)

2. Time at temperature is 1 hour, also in agreement with the PQR.

3. Gas variables are not required for SMAW.

The WPS

We will now complete the bottom half of the back of the WPS. Which consists of the Technique box QW-410 only.

The WPS1. String or Weave, restricted from 2 to 3 core

diameters (core wire exclusive of any coating).

2. Cleaning is limited to Brushing or Grinding. Back Gouging will be by Air Carbon Arc.

3. Multiple Pass, Single Electrode ( not required), but often entered. Manual is entered in the heading of the WPS and Peening is listed as not allowed.

4. All others are not SMAW variables.

The Complete WPS Front

The Complete WPS Back

Lesson 13 wriiting a wps by_essential_new2

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Transcript of Lesson 13 wriiting a wps by_essential_new2