Re: Re: [MW:29824] HIGH HARDNESS AFTER PWHT (ER70S-2)

Check the below points are met,

Test Personnel follow step by step method for hardness testing using Portable Brinell Hardness Tester in accordance with ASTM E 10 or with a comparison hardness tester in accordance with ASTM A 833– 08a.                                                                                   Note 1: Procedure is available & personnel are trained in its use.                           Note 2: Applicable project specs reflect this: NACE HT Exemption based on welding processes in NACE SP0472 are not applied at SA.

NACE SP0472- Para 2.2.7.3

EXTREME CARE shall be taken when grinding welds flat (Flat-top) to prevent any / minimize base metal removal. Base metal removal was checked by Inspection. No need exists for additional NDE (UT, etc) to verify adequate remaining wall exists per material specs.

ASTM A 833 – 08a                            Para 5

A 1 to 21⁄4 (2-5 lb) hammer for Telebrinell Portable Hardness Testers (BHT) is being used. "As stamped" hammer head weight at 2-5 lb has been verified to assure reliable HT results.                                                                                                            Note: Tests performed with incorrect weight hammer are invalid.

ASTM A 833 – 08a                            Para 7

Test bars are available for test verification by QC & SA Inspection. Visual verification of test bars & Production welds shall verify that proper BHT technique is used. Double impressions and use of more than 2 adjacent sides is not allowed. Technicians made indentations within .1mm roundness tolerance & followed the 12-step procedure                                            Note: Call for retraining & closer supervision* (Witness/Hold) for any deficiencies found during witness of technician performance.

ASTM A 833 – 08a                            Para 6

System for identifying rejected readings (Retests) on Test bars & Production welds was followed. Indentations found out-of-round, double impressions, out of 3-4 mm range, etc, require retesting. Permanent mark (Sharpy pen, etc) "X" was placed over the invalid indentation(s) for retest. Welds unmarked with unacceptable indentations on Production welds shall be investigated and retested to extent necessary to ensure valid Brinell Hardness test results.                                                                                                                                                              Identify invalid test results & ensure Quality of HT results

NACE SP0472                          Para 2.2.7.8

Weld deposits were hardness tested on the side contacting service process whenever possible. If process side access is impractical, (piping or small diameter vessels), HT was done on opposite side.                                                                                                                         Sample accessible internal welds "randomly" & safely.

NACE SP0472, Para 2.2.7.2

BHT shall not be performed until AFTER welds are sufficiently cool and an adequate time period has elapsed to ensure valid HT results.                              WPS & Specification special instructions for PWHT & BHT were followed. (No Delayed Hydrogen cracking concerns exist).

AS per project Sch. Q,                                              NACE SP0472

Criteria is Properly Evaluated: If any reading exceeds specified limits by no more than 10 BHN, a minimum of (3) additional readings shall be made near the original high reading. If all (3) retests are below specified limits, then the joint is acceptable. If any retest reading(s) exceed specified limits, the weld is unacceptable.                                                  This is a common requirement for all SA applications

ALL                             SAES-W-STDs                                  Plant Piping, Pipelines,                               Vessels &                     API Tanks

Verify: If any welds are found to be unacceptable, then two additional welds from the same lot* shall be tested. If more than one weld in a lot is found unacceptable, then all welds in that lot shall be tested. (Plant Piping, Pipelines as applicable).                                                                                        Note 1: Applies to Sour Service welds tested (10%). Additional welds selected shall be from same welder. Sample all welders.                                           Note 2: Furnace "Batch" welds PWHT & HT'd at 10% rate, ANY result unacceptable shall be cause for entire "batch" to be tested.

PLANT PIPING    SAES-W-011, Para. 14.5

Attachment  1 - ASTM A 833 – 08a

Portable Brinell Hardness Testing (BHT) of Welds

1. Finish—When necessary, the surface on which the impression is to be made shall be filed, ground, machined, or polished with abrasive material so that the edge of the impression shall be defined clearly enough to permit the measurement of the diameter to the specified accuracy. Take care to avoid overheating or cold working the surface. Sufficient metal shall be removed to eliminate decarburized metal.

2.Assemble the comparative test bar into the apparatus making sure a minimum distance of no less than 5 mm will exist between diameter of the impression to be made and any other indentations on the face. Minimum distance of the indentation diameter from the edge of the part tested shall be 12.5 mm.

3. If the apparatus is equipped with a presetting bar stop, ensure the fixture is properly in place.

4. Ensure that the hardness test block is flat on the test surface.

5.Apply the impact load using a 1 to 21⁄4kg (2 to 5 lb) hammer. It is essential to apply a well guided, short blow in order to avoid a rebound and thus a double blow that may produce an erroneous result by damaging the sharp edge of the ball impression.

6.Impression Diameter—The diameter of the impression produced on the comparative test bar should not exceed 4.2 mm. If a larger impression is produced, the comparative bar may give way laterally and the test result may be in error. In this case the use of the 1500-kg load should be considered (see ASTM A 833-08, para6.2).

7. Measurements— Two diameters of each impression at right angles to each other shall be measured to within 0.05 mm and their mean value used as the basis for subsequent calculations. If the two diameter measurements differ by more than 0.1 mm, the readings shall be discarded in accordance with Test Methods and Definitions A 370, and the test repeated.

8. Determination of Part Hardness—Employing the calibration device or mathematical equation supplied by the manufacturer for the apparatus, determine the hardness of the part by using both (test bar and part) impression diameters and the hardness of the comparative bar in accordance with the equipment manufacturer's instructions.

9. Report:  The report shall include the following information. 9.1. Indentation hardness number of the part or component as calculated in 8 with the designation HBC and the Brinell hardness number of the comparative test bar, 9.1.1. The result shall be written as shown in the following example: 232HBC/240 where 232 is the hardness determined as defined in 8 and 240 is the Brinell hardness of the comparative test bar. 9.2 Identification of the manufacturer's equipment, and 9.3 Diameters of the impressions in the part or component and comparative test bar. comparative test bar.

10.Repair welds in cast, forged, or plate components shall be hardness tested, when required, in accordance with the NACE SP 0472 Para 2.2.7.7:

11. All hardness impressions at one test location should have at least 6.4 mm (0.25 in.) between their nearest edges.

12. Hardness impressions can be made on only two adjacent sides of the hardness test bars.

13. Replace indenter ball when it is out-of-round. (Inspect & rotate ball regularly, disassemble to rotate & inspect for flat spots)

REFERENCE (TEST) BAR REQUIREMENTS

Note: Brinell Hardness Testing (BHT) is a self-calibrating method based on hardness impression comparison. Reference bars are M&TE, simply Calibration standards of "Known" Material Composition & Hardness Values. (SAEP-355, Sect 6)

BHT Reference (Test) Bars are M&TE and shall:

1. Be from a Certified source (QC Record, CMTRs) to attest to their quality & HT Value per their applicable ASTM mfg requirements.

2. Have their hardness value clearly marked at the ends of each bar by the manufacturer.

3. Test Bar Selection (Material type & Hardness value) shall be selected to be "SIMILAR" to the test piece. (SAEP-355, Section 6)

3a. Test Bar Material shall be the same P-No as the Test Piece, unless CSD specifies otherwise.

3b. Test Bar Hardness Value shall be within +/- 10% of Maximum Specified Hardness (either 200 BNH, 225, 235, 248) allowed by SA.

NOTE: SELECT CORRECT "RANGE" OF TEST BARS: A range of test bars (100 - 400 BHN are sold) is required for BHT Test bars for production work must be within +/- 10% of maximum specified Hardness (200 for Sour Service, ALL PLANT PIPING), 200 for vessel work or as specified bu User. Check job specs for Matls to be PWHT (Piping Line Class, Data Sheets) as applicable. Before work begins, ensure an available range/adequate supply of test bars is based on "KNOWN" material specs (CMTRs).

3c. RETESTING PRACTICE & INVESTIGATION OF UNACCEPTABLE RESULTS FOLLOW EXAMPLES BELOW

Example 1: A 188 BHN value test bar is used for HT of welds (200 BHN Sour Service line, test bar is P-No-1, within +/- 10% of max BHN). Test results show 159 BHN value. Per Step # 9 of procedure, the result is invalid & retesting is required & should be performed with a bar of a hardness value closer to 159 BHN value to obtain a valid result, even if it is below 200. Retests with same bar will result in retesting (over & over again). Per CSD, this general retest policy is waived and is unnecessary as the final result will be under 200 & acceptable.

Example 2: Same 188 BHN value test bar is used for testing (235 BHN P-No 5 Heater Tubes ASTM A335, bar is the wrong P-No mat'l & not within +/- 10% of Max BHN value). Test bar must be selected per Example # 1 & P-No 5 Test bars of higher HT value are needed.

Example 3:  A 225 BHN value test bar is obtained for testing Example # 2 Heater Tubes (P-5 mat'l within +/- 10% of Max BHN value). Weld readings (U-bends) show 351 BHN value. Metallurgical Investigation of U-bends & welds finds all sampled readings (300+) using correct range of test bars. Investigation follows. CSD rejects the welds & requires PWHT & RT (disposition). Further investigation revealed that the Heater Tubes (over 3,000 total) were never PWHT'd, yet all had been accepted by HT reports using Equotip method. See Checklist Item D5.

Alternative Hardness Testing Equipment (2 Approved by CSD) for Branch Connection & Fillet welds, etc

1. Krautkramer Microdur 10 (MIC-10) is one of two equipment types allowed. Rebound type or Leeb portable testers that use spring-loaded probes (specifically Proceq Equotip and others) are prohibited for use in SA. (See SAEP-355, Para. 6.2.1). Krautkramer Microdur MIC 10 portable hardness testers require a careful selection of interchangeable probes to obtain Hardness readings from welds with geometries inaccessible to BHT (branch connections, fillets, curved/convex surfaces, etc). Provide/document/demonstrate operator training. Careful test surface prep (fine grind/finish, 400 grit per CSD for reliable result) is required. Verify 10% of MIC-10 readings by  BHT comparison. (Once daily with testing/minimum). Take BHT readings as close as possible to MIC-10 readings, accuracy to be within 10% with acceptable BHT results. (NACE MR 0175,  owner/user option for alternative equip).                                                                                                                                                                                  2. MIC-20 & later generations of Krautkramer Microdur technology can be applied (pending CSD approval).

1a. Krautkramer Microdur 10 (MIC-10) Manual Probes req'd for tight convex geometries are: Article (Model) MIC 201/ 205 with Test Load 10 N (1 kgf) / 50N (5 kgf). Portable kits must have calibration standards of known Rockwell Hardness, Hardness Conversion Tables, instructions & laminated cards for calibration (Keep these on site with equipment to demonstrate calibration accuracy)

2. MiniBrineller (a miniature version of the Telebrinell) is also acceptable per CSD. Information on these unit complete kits can be obtained @ http://www.ndtech.net/products/minibrineller.html  Verify 5-10% of Minibrineller readings by BHT (Telebrinell), same as MIC-10.

Yours

MOHAMED MUNEEB MAHABOOB

+91-786-700-444-6      TRZ - INDIA

''quality is not your cup of tea to waive as per your own business conditions - quality is that tree fixed firmly deep rooted, in which each root is an evidence of references''

 

From: Sudheer Babu

Date: 2019-07-12 14:38

To: materials-welding

Subject: Re: [MW:29822] HIGH HARDNESS AFTER PWHT (ER70S-2)

Yes better to change the filler wire / make and check again.

Sudheer Babu Nelapati

On Fri, Jul 12, 2019 at 6:22 AM Raghuram Bathula <raghurambathula@gmail.com> wrote:

Intersting Mr Kondori

Do you have any refernace or research paper on this subject?

Thanks

On Thu, 11 Jul 2019 at 09:23, Ramin Kondori <raminkondori@gmail.com> wrote:

Hello,

ER 70S-2 is a triple deoxidized steel welding wire. 

It has Ti, Zr, and Al additions (please check your filler metal certificate).

After PWHT, these elements can increase the hardness of weld metal (but not HAZ or base metal). Many do not consider this when choosing filler metal.

 

I recommend you to conduct a chemical analysis examination on both the filler metal (rod or electrode) and production weld metal and revert back to us. 

Regards

Ramin  Kondori

Sr. QA/QC & Welding Engineer

-----------------------------------------------------------

PG-Dip. in Welding Engineering (IWE  AT  0070)

BSc. in Civil Engineering (IUT)

BGAS Painting Inspector

ASNT Level I&II

                        

On Wed, Jul 10, 2019 at 2:11 PM Karthikeyan Muthuvel <m.karthick2020@gmail.com> wrote:

Dear Experts,

Good day.

We had used the consumables (ER70S-2) / OK TIG ROD 12.62, Size : 2.4mm Dia. for our Production weld joints (Pipe materials : Carbon Steel ASTM A 106 Gr. B; Size : 3" X Sch 40). further to inform you that we had checked the Hardness of Base material , HAZ & on weld Metal before & after PWHT (below hardness readings were observed).

HARDNESS VALUES BEFORE PWHT

1. Base material : 130 to 150 HB
2. Heat Affected Zone : 140 to 160 HB
3. Weld Metal : 170 to 190 HB

HARDNESS VALUES AFTER PWHT 

1. Base material : 120 to 140 HB
2. Heat Affected Zone : 130 to 150 HB
3. Weld Metal : 210 to 250 HB

After performing PWHT the hardness value of Base material & Heat Affected Zone has been reduced. whereas the Hardness value of Weld Deposition has been increased (which is beyond the acceptable limit). 

So, I would like to know from you that what might be the technical reason/root cause for increase in hardness only on the weld joint after PWHT. 

Below are the PWHT parameters fyi.

Soaking Temp. : 620 Deg C

Soaking Time : 1 hr.

Rate of Heating : 100 Deg C per Hour (from 100 Deg C)

Rate of Cooling : 100 Deg C per Hour (Upto 100 Deg C)

Note:

1. We had performed nearly 30Nos. of Production joints & we had face the problem of Hardness on all the weld joints. 
2. Hardness was tested using Mic 10 tester method ( even cross verified with Equotip method & Tele brinell Method)

Thank you for your support.

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