11.23 SPLICING PILE

Welding Steel Pile
Specification 2408.13 requires that all welds conform to the Structural Welding Code ANSI/AWS D1.1 of the American Welding Society.
A. Field Welding
All welding must be done by a certified welder. When a welder is qualified by the Office of Materials, a certificate is issued showing the types of welds which they are qualified to perform. Inspectors should ask to see the welder's certificate, and note: (1) certificate number, (2) date issued, and (3) qualified positions on the "Log of Piling" form. Certificates are good for one year and must be renewed annually, except requalification will only be required every two years for field welders who have successfully passed their qualification tests without failure for three consecutive years.

Only Shielded Metal Arc Welding (SMAW) and Flux Cored Arc Welding (FCAW) will be permitted for welding steel piles.

The welding electrode must be on the approved list published by the Office of Materials semiannually or be specifically approved by the Office of Materials.

B. Shell Pile

Shell pile manufactured by Union Metal require splices to be fillet welded. The fillet weld should be equal in size to the thickness of the shell wall. The pile extension must be telescoped into the pile to be extended a minimum of 150 mm (6 inches). For splicing pile manufactured by Armco, a butt joint and square groove weld must be used as shown in Figure A, Appendix 11-4.

C. Pipe Piles

Pipe pile may be extended using Figure A, or B, or C (Appendix 11-4) depending on wall thickness and pile position at the time of splicing.

D. Steel H-Piles

Specifications require that field extensions of Steel H-piles shall be made only by approved welding procedures involving the use of backing plates. Steel H-piles are extended with a butt joint requiring a single-bevel groove weld when welded in the horizontal position (Figure B, Appendix 11-4) and a vee groove weld in the flat position (Figure C, Appendix 11-4). The backing plate must be at least 6 mm (1/4 inch) thick, 38 mm (1-1/2 inches) wide and of the required length to extend full width of web and flanges. Note:  HP 360 mm x 174 kg (HP 14 x 117) steel H-piles require a special welding procedure due to flange thickness.

If a backing plate thickness of more than 10 mm (3/8 inch) is used, weld the backing plate all around with a fillet weld. A backing plate 6 mm to 10 mm (1/4 to 3/8 inch) thick may be tack welded in place.  Backing plates must be bent or ground to fit snug against the flanges, web, and have chambered corners to fit between the flanges and web.  The required root opening is 6 mm (1/4 inch) with a tolerance of plus 6 mm (1/4 inch) and minus 2 mm (1/16 inch).

The top of the pile being extended must be cut square with flat ends; the lower end of the extension, both flanges and web, must be beveled to a 45^o angle (Figure B, Appendix 11-4). The groove angle in the flat position is to be cut to a 45^o included angle as shown in Figure C, Appendix 11-4. The tolerance of a groove angle joint is ±5^o. The root face of the weld joints in Figures B and C shall be no greater than 2 mm (1/16 inch).  When welding H piles, the web must be welded first.

E. Surface Roughness

Grinding will be required on all free hand oxygen cut joints to achieve the proper angles and surface smoothness. The roughness of oxygen cut surfaces shall not be greater than 25 micrometers  (1,000 micro-inches) as compared to a Surface Roughness Scale. The inspector should occasionally spot check joint preparation for roughness, prior to welding.
Rule-of-thumb: The "feel" of scraping your fingernail over the edge of a used penny or nickel will approximate the maximum roughness allowed on oxygen cut surfaces.

F. Pile Alignment

Sections of piles to be joined by butt welds shall be carefully aligned. Should the end of the pile to be extended be bent from driving, the bent portion of the pile shall be cut off. In aligning the piles for welding, the webs shall be brought into alignment first. If there is some slight dimensional variation due to fabrication, the pile extension shall be centered so that eccentricity of the flanges is reduced to a minimum.

G. Welder Certification

Welders qualified to work on Iowa DOT projects are qualified on 10 mm (3/8 inch) plates. The maximum thickness of plates that may be welded from one side under our normal certification is 19 mm (3/4 inch). If material thicker than 19 mm (3/4 inch) is to be welded, for example an HP 360 x 174 (HP 14 x 117), qualification tests on 25 mm (1 inch) plates will be required.

H. Welding Electrode and Preheat Requirements

The requirements regarding procedures for welding electrodes and preheating temperatures for the various types of steel piling are as follows:

NOTE: Preheating of electrodes requires an "electrode oven" to be on-site and used!

1. Welding must be done with the same process (SMAW or FCAW) used for qualification.
2. If the operator has qualified on welding ASTM 36 steel, that same operator is qualified to weld on steel meeting the requirements of ASTM A572 grade 50 (H-pile), ASTM A328 (sheet pile) and ASTM A252 (pipe pile) grade 2 or 3.
3. A welder qualified for manual shielded metal-arc welding with an E 7018 electrode may also weld with E 7016 and E 7028 electrodes. For welding steel piles, E 7018 and E 7016 electrodes are preferred.

Identifying electrode numbers are as follows:

• The 70 designation shall be understood to mean the 70 series unless an alloy steel of higher strength is to be welded.
• The third digit indicates the position permitted.  If the digit is "1," the electrode may be used for welding in any position. If "2," only the down hand position may be used.
• The fourth digit indicates the chemical make-up of the electrode coating. The digit 6 indicates low hydrogen potassium, and 8 a low hydrogen iron powder.

Preheating of the base metal means that the surfaces of the parts being welded, within 75 mm (3 inches) laterally and in advance of the welding, must be at or above the following prescribed temperature:

1. For A572 grade 50 steel (H-pile), A328 (sheet pile) and A252 (pipe pile) grade 2 or 3, up to and including 19 mm (3/4 inch) thickness, when welding with low hydrogen electrodes the preheat temperature requirement shall be 10^o C (50^o F). For thickness over 19 mm (3/4 inch) the preheat temperature requirement shall be 21^o C (70^o F).

Welding when the ambient temperature is below –18^o C (0^o F) is not permitted.  In inclement or windy weather, suitable shielding must be provided to permit welding in the normal manner.

All electrodes having low hydrogen coverings shall be purchased in hermetically sealed containers or shall be dried for at least two hours between 232^o C and 260^o C (450^o F and 500^o F) before being used. Immediately after drying or removal from hermetically sealed containers, electrodes shall be kept in storage ovens of at least 121^o C (250^o F).  Electrodes not used within four hours after removal from the drying or storage oven must be redried before use. For the ordinary field pile welding job, electrodes should be purchased in small packages, allowing for use within the prescribed time limit, unless provision for storage at 121^o C (250^o F) is made.

Preference of E 7016 and E 7018 electrodes for field welding may now be apparent. The digit 1 permits welding in all positions. These electrode coatings are low in hydrogen, permitting use on A36 and SAE 1010 steels without preheating the base metal unless the temperature is below 10^o C (50^o F).  These electrodes are also required for making the prequalification test.

The restrictions and rules for preheating as outlined above cover the welding of all of our steel piling, since they apply to steel up to 19 mm (3/4 inch) thick.  If welding is required on thicker plates, other special rules apply. In such case, the Office of Materials should be contacted for assistance.

Electrodes that are allowed for Flux Cored Arc Welding are E60T-1, E60T-5, E60T-6, E60T-8, E70T-1, E70T-5, E70T-6, or E70T-8. When welding ASTM A588 steel, only the E70 series may be used.

Concrete Pile
A. Extending Concrete Pile

One of the major disadvantages of concrete piles stems from the difficulty of cutoff and extension. If extension of 355 mm or 405 mm (14 or 16 inch) concrete piles is required, the method of extension shall be at the direction of the project engineer. For the purposes of example, the following steps are one method which could be used:
1. Splicing Non-Prestressed Precast Piles
When a precast, non-prestressed concrete pile must be extended, the concrete at the end must be cut away to expose at least twenty (20) diameters and not less than 0.6 m (24 inches) of the longitudinal reinforcing bar.  Reinforcing steel of the same size are spliced by being securely wired to the projecting steel.
2. Splicing Prestressed Precast Piles
If the pile is prestressed, the concrete at the end must be cut away to expose at least 0.6 m (24 inches) of the prestressing tendons. Reinforcing of equal size must be securely wired to the exposed steel. Furthermore, the extension must have 0.53 mm diameter (5 gauge) spiral reinforcing at 75 mm (3 inch) pitch ending with 6 close turns at the top.

After the extension steel is wired securely in place, the forms may be set. Care must be taken to prevent concrete leakage along the face of the pile and to prevent any bulging of the forms. Concrete used in the extension must be of the same quality as used in the original piling. Just prior to placing concrete, the top must have a grout coating to help assure bonding.

B. Splicing 305 mm (12 inch) Concrete Piles

These piling are designed to improve splicing and/or extending by having a steel plate cast into the pile top. If extension becomes necessary, the extension pile also comes with a steel plate cast into its lower end. Splicing then becomes a matter of setting the extension on top and welding the two plates together. (Refer to Figure D, Appendix 11-4 for welding information.)

Field evaluation conducted in the summer of 1993 indicates the splicing method is very successful.

11.24 PILING ACCEPTANCE

Steel Pile
For acceptance of steel piling refer to Materials I.M. 467.  This I.M. has undergone a general rewrite. Acceptance for incorporation of steel pile into a project will be based on an approved certified mill analysis of the steel and a satisfactory report on any random sample secured from a project and tested by the Central Laboratory.  Approved producing mills are listed in Appendix A of this I.M.

Steel piling will not be tested for acceptance on every project. Monitor sampling on a random basis will be coordinated by each District Materials Engineer. Testing of random monitor samples will be processed in the Central Laboratory.

Any random test sample that fails to comply with the requirements and tolerances (dimension and mass) will be handled on an individual basis as directed by the Materials Engineer.

Wood Pile
A. Documentation and Acceptance

At times, wood piling have been delivered to a project from a nearby supplier well ahead of reports for testing and approval. Before the piling are driven, we must assure ourselves that material testing has been completed, and that the District Materials Office has recorded identification markings and/or tags from each lot of piling.

One or both ends of the piling have 3 marks which identify:
1. Treatment charge number (hammer mark or metal tag - could be on the face of a pile)
2. Inspection agency mark
3. Length of piling

Materials IM-462, Appendix B has a list of inspection agencies approved to supply wood piling to Iowa DOT projects. The piles are identified by the initials of these inspection agencies and the inspector's number. It is important that these inspection identification marks be listed in the inspectors field book, along with a record of material and test reports received for the project.

B. Treating Wood Pile

Specifications 2409.05 and 2501.15 require treating cutoff wood pile before incorporating into the structure. A preservative approved by Specifications 4160 and/or 4161 shall be used.

C. Purchase and Return of Piling

Specification 2501.21, Paragraph A gives a contracting authority the right to purchase unused piling at cost plus 10% as an overhead cost. This would be the cost to the contractor including such items as invoice cost, delivery cost, handling cost at the job site, and any delivery cost to a storage site.

NOTE:  On primary projects, it will be Iowa DOT's general policy not to purchase unused piling.

Steel Pile Cutoffs
If the contractor feels the cutoff is long enough that they may use it on some future project, the Heat number should be placed on the cutoff and a number to indicate the project it came from.

11.25 WAVE EQUATION

Hammer Data Form
Input data for the wave equation program is provided on the "HAMMER DATA" sheet.  The blank forms are suggested to be sent to the contractor when arranging for a preconstruction conference.

Completed data sheets shall be returned to the project engineer for forwarding to the Office of Construction at least 20 days prior to driving piling. Prior to forwarding, the project inspector needs to review the forms for completeness. Such screening will help to eliminate delays later. Check the following:

• The hammer data area is fully filled out.
• The piling are listed as indicated on the plans for size, length, and design bearing.
• A hammer cushion is listed.  (Cushion #1.)  This is required for every hammer.
• If driving concrete piling, there must be a pile cushion listed. (Cushion #2.)
• For gravity hammers, be sure that ram dimensions are given.

If a "HAMMER DATA" form is lacking any of the above information, contact the contractor and obtain the missing data before forwarding the data sheet to the Office of Construction.

Once the driving graphs have been produced, the "HAMMER DATA" sheet will be returned with a graph number added in the "FOR OFFICIAL USE ONLY" column.  This ties the data sheet to a particular driving graph.  Use the data sheet as a field "equipment" checklist.

NOTE: It is mandatory that the inspector verify all hammer data prior to beginning pile driving.

All information is important. Make certain the type, dimension, and thickness of the hammer cushions are correct. If there are doubts about the cushion, check it in the field. Hammer cushions should be inspected periodically during the project to verify thickness and condition. Damaged or deteriorated cushions must be replaced.

Refer to HAMMER DATA forms in Appendix 11-5. Since these forms are not in the Office Supply system, please photocopy as needed.

Driving Graphs
The curves of driving resistance versus blow count, and stress versus blow count, are plotted from the summary output generated by a computer analysis. Since the results of analysis depend on 1) pile length, 2) embedded pile length, and 3) the soil "N" values, curves usually are generated for embedded lengths in 3 meter (10-foot) increments. If the addition of pile causes the length to penetrate into a new "N" value, a new graph should be developed. If a variable stroke hammer is to be used, curves will be generated for several stroke heights.

For inspection purposes, the use of driving graphs is extremely easy. Inspectors only need to record the number of blows required to move the pile an equivalent of 0.25 m (1 foot), find that number of blows per 0.25 m (foot) on the "X" axis, read upward to the graphed line representing the appropriate drop height, and record the driven resistance which corresponds on the "Y" axis.

EXAMPLE: Assume:	(Refer to Example in Appendix 11-6.1) (Given in U.S. units) 1. Hammer drop = 5' 2. Inspector records 80 blows per foot 3. HP 10 x 42 pile
Question:	What is the driven resistance?
Procedure:	1. Find 80 BPF on the "X" axis (Point A) 2. Move vertically upward to the 5' stroke line (Point B) 3. Move horizontally to the "Y" axis (Point C) 4. Read and record 48 tons
EXAMPLE: Assume:	(Refer to Example in Appendix 11-6.2) (Given in metric units) 1.  Hammer drop = 2.25 m 2.  Inspector records 98 blows per 0.25 m 3.  HP 250 x 62 pile
Question:	What is the driven resistance?
Procedure:	1.  Find 98 blows per 0.25 m on the “X” axis (Point A) 2.  Move upward to the 2.25 m stroke line (Point B) 3.  Move horizontally to the “Y” axis (Point C) 4.  Read and record 712 kN

NOTE:  Driving graphs are produced for a particular location, using a specific hammer, and type of pile. In this example, HP 10 x 42 pile are being driven. Since there are no restrictions listed in the upper left-hand corner of the driving graph, the inspector may use the entire graph.  The lack of restrictions means that this hammer is not capable of over-stressing the pile for the plotted strokes and listed blows per foot.

Several important aspects of the driving graph should be noted and observed:

• Any driving graph is for a specified design number and foundation unit and is computed based on specific hammer data.  The inspector MUST be sure all listed hammer data are checked in the field.
• Driving graphs prepared in the Office of Construction account for ultimate resistance.  For City and County projects, be sure the driving graph includes, and lists a "Factor of Safety," and provides information relative to driving stresses."
• The graphed lines are "best-fit" lines drawn from several computer generated points.  Based on the graph scale, reading to fractions or tenths of a ton is most likely inappropriate.
• Any graphed line may be interpolated between given lines.
• Often during final driving or a retap, only blows per fraction of a meter (foot) can be observed.  If this is the case, convert to blows per 0.25 m (foot) and evaluate as usual.

EXAMPLE: Assume:	(Given in U.S. units only.) 1. Hammer drop = 5' 2. Retap condition 3. Inspector records 17 blows per 6 inches of penetration
Question:	1. What is the value in "blows per foot?" 2. What is the driven resistance for this retap?
Procedure:	1. Convert to blows per foot (BPF)     X   =   12"    17        6"                       X = 34 BPF 2.  Find 34 BPF on the "X" axis and proceed as in previous example to determine driven resistance

• For wood piling, Specification 2501.16 limits driving of wood pile to 40 ton or less.
• All types of pile have varying driving stress limits. Values given in the upper left-hand corner provide important information to the inspector about driving stresses. By drawing a horizontal line corresponding to a particular maximum value (** DO NOT EXCEED **) and Begin to Monitor, the driving graph provides a convenient way to monitor and check these maximum and precautionary values.

Log of Piling Driven
The "Log of Piling Driven" form is used on all projects to document relevant "as constructed" pile information. This report shows a bearing obtained for each individual pile driven and overall length incorporated into the structure. The project engineer should prepare two photocopies of the original report:

• One copy is to be retained in project files.
• One copy is forwarded to the District Office for their records.
• The original is to be sent to the Office of Construction. This copy will be reviewed and ultimately forwarded to the Office of Bridges and Structures where it becomes a part of the structure's permanent record.

Before signing the report, the project engineer should be sure the report has been verified through an independent check. A copy of the driving graph needs to be included when information is forwarded for future reference. One way to do this is to photocopy the driving graph on the back of each "LOG OF PILING DRIVEN" sheet. The bearing value of the piles should be recorded to the nearest "readable" graphed bearing value.

The length of piles shown on plans or ordered by the project engineer indicates the desired penetration. Although the specified bearing may have been obtained prior to "full" penetration, driving shall be continued until full penetration is secured so long as a pile can be driven without damage. If specified bearing is not achieved or full penetration is not obtained to within 3 meters (10 feet) of the plan pile length, contact the Office of Construction for review of driving results.

Log down one piling in each foundation of every structure. Logging the first pile in each foundation will provide beneficial information for the contractor and inspector during production pile driving. The logged results represent the actual driving resistance for the full length of the pile as it is driven through successive soil layers. This logged pile driving resistance can be compared with the plan soil profile and soil boring sheets to evaluate driving conditions during production pile driving. This logged pile information will also be important when pile capacity and/or pile penetration problems are discussed with the Office of Construction.

The following are general guidelines for logging pile. If driving is hard, record intervals at 0.6 to 1 m (2 to 3 feet)  If little resistance to driving is encountered, 1.3 to 1.5 m (4 to 5 foot) intervals would be sufficient.  This information should be entered on a separate log of piling form and forwarded with the production "Log of Piling Driven." The logged piling data should include all the usual information required on the regular Log of Piling Driven.

Refer to "LOG OF PILING DRIVEN" report in Appendix 11-7. These forms are available from Office Supplies (Form 830209). The metric version of the "Log of Piling Driven" (Form 830209M) is included in Appendix 11-7 and is available from the Office of Construction.

A. Filling Out the Report

Columns for plan length and extensions should be totaled and length measured for payment should be shown on the report as the sample report illustrates.  (Refer to example in Appendix 11-8.) When it is necessary to extend pile, the length of extension is placed on the "Log of Piling Driven" report in the appropriate column. The number of field splices required shall be reported.

If welding of piling is necessary (i.e., splicing), add the following information to the "Log of Piling Driven" form:
1. Name of certified welder(s)
2. Certificate number(s)
3. Date(s) piles were welded

B. Numbering of Piles on Foundation Sketches

A suggested method of numbering piling on pile log sketches to obtain uniformity and ease of identification is provided in Appendix 11-9.

Number piles in abutment footings from left to right when facing up station. Also facing up station, number piles in pier footings starting at the upper left corner from left to right and continuing for each row in the footing.  Multiple footings can be numbered in the same manner. Single row pile pier bents can be numbered from left to right.