The quarterly newsletter from Phoenix National Laboratories that focuses on quality, testing technology, and inspection trends
PNL is excited to announce a new service for 2022 in our continuing effort to provide the highest quality testing services. PNL now offers both FTIR bulk and micro analysis capabilities. Fourier Transform Infrared Spectroscopy (FTIR) allows for the analysis in a wide range of applications, especially related to polymeric and organic compounds. The technique is widely used for identification in parallel with quality and process control and the ability for micro FTIR analysis allows PNL to offer a unique service not readily available in the Valley.
Feel free to contact Amber Trees, PE (firstname.lastname@example.org) with any inquiries about FTIR/micro analysis or any of your material and metallurgical testing requests.
In the United States alone there are an average of 100 deaths per year caused by confined spaces accidents. This statistic represents two individual tragedies per week in the workplace. It is estimated that 60% of the fatalities occurring in confined spaces involve the “would be rescuers.” These hazardous environments exist in the construction, oil and gas, mining, trucking, agriculture, manufacturing, public works, nautical and a multitude of industries.
“Confined Space” means a space that: 1. Is large enough and so configured that an employee can bodily enter and perform assigned work; and 2. Has limited or restricted means for entry or exit and 3. Is not designated for continuous employee occupancy. Examples of Confined Spaces are tanks, vessels, manholes, boilers, furnaces, sewers, silos, hoppers, vaults, pipes, trenches, tunnels, ducts, bins and pits.
The potential hazards in confined spaces are Oxygen Deficiency, Combustibles, Toxic Materials, Electricity, and Mechanical Hazards. Entry is considered to be the act by which a person intentionally passes through an opening into a confined space or any part of the body passing through the opening of a confined space.
Prior to entering a confined space each employer is responsible for evaluating the confined space and to establish entry, attendant, and rescue services. This is most often done by the owner of the confined space, but not always. Each person entering a confined space must be trained and understand the hazards and risks with making entry. Some spaces must be permitted using a Confined Space Entry Permit which is posted at the job site before and during entry. The document includes location and description of entry, purpose, start date and time, entry supervisor, authorized entrants, permit space hazards, special requirements (atmospheric) levels of toxic gases, permissible levels, pre-entry levels, levels after isolation and ventilation, emergency procedures, and authorization by Entry Supervisor. Permit required confined space means a space that has one or more of the following characteristics:
A Non-Permit Confined Space is a confined space that does not contain or have the potential to contain any hazard capable of causing death or serious physical harm. Before entering any confined space, each person should ensure that the space poses no actual or potentially hazardous atmospheres, all hazards within the space have been eliminated such as locking and tagging equipment, and have notified a responsible person prior to entering the space. Recently in Phoenix two truck drivers tragically died from exposure to an unknown residual chemical substance when they were trapped inside the empty tanker vault of a semi-truck. For those companies who do not regularly employ workers who perform their jobs in confined spaces, it is easy to forget how dangerous working in these types of spaces can be. The troubling reality is that any danger that could otherwise be encountered in the workplace can also occur in a confined space. The critical issue to consider is that these hazards will be much more severe in an area where entry and exit are limited. We appreciate all the workers worldwide who perform important services who take special precautions and risks in confined spaces.
Technician working in a vessel
Special Inspections are defined in the International Building Code (IBC) Section 1704 as those inspections to verify that work is considered critical to life safety and property protection is being or has been constructed according to the approved plans and specifications. These inspections are in addition to the typical city or county inspections required by the jurisdictional building department or specific structural observations conducted by the Engineer. The inspection of high strength bolts is one such special inspection.
High Strength Bolt Tensioning
This issue of PNL Quality Examiner focuses on the special inspection of High Strength Bolting and highlights the Skidmore-Wilhelm Test to perform lot testing. The manufacturer developed the first Bolt Tension Calibrator for the construction industry in response to their need to test high strength bolts on site. The Hydraulic tension calibrator, or bolt tension calibrator has been the industry standard for testing high-strength bolts since they invented the technology in the 1950’s. Their units are required to be used on steel buildings, bridges and other structures using fasteners in tension critical joints. The units can safely be used with hand torque wrenches, impact guns, electric wrenches and hydraulic wrenches.
The Specification for Structural Joints Using High-Strength Bolts published by the Research Council on Structural Connections and found in the AISC Steel Construction Manual governs the use of high strength bolts, including design, installation, and inspections. Prior to installing high strength bolts, a representative sample of not fewer than three complete fastener assemblies of each combination of diameter, length, grade, and lot to be used in the work shall be checked at the site of installation in a tension calibrator to verify that the the bolts and installation method used to install the bolts result in applying the proper tension on the bolt. Bolt tension is important to ensure the connection transfers loads between the plates and not through the bolts. This is accomplished by the clamping force applied to the connection by tensioning the bolts. The amount of clamping force (N), or bolt tension x the coefficient of friction (μ), which is dependent upon the surface roughness between the plates, determines the maximum shear force that can be safely applied without the plates moving. See Figure 1 for the tension diagram.
Friction Force: F = μN
The structural design engineer will use the bolt pre-tensioning values found in Table 7.1 of the Specification for Structural Joints Using High-Strength Bolts to determine the size and number of bolts needed to resist the loads imposed on the structure. So, it is important to ensure the bolting system works as intended. The approximate 30-minute video featured in our Tech Talk segment shows how the Skidmore-Wihelm bolt tensioner works to test the bolt lots prior to installation.
PNL Tech Talk provides insights into the testing and inspection industry from a technician's viewpoint and gives a close-up look at the day-to-day life working at PNL. It may include interviews with one of our technicians, or vendors who support our services, or an editorial written by one of our technicians. This quarter’s feature explores issues in Special Inspections with a video demonstration of the Skidmore-Wilhelm high strength bolting test.
The ASME B31.3 Code for Process Piping identifies specific fluid service categories based on the type, temperature, and pressure of the fluid flowing within a piping system. These services include Category D, Category M, Elevated Temperature, High Pressure, High Purity and Normal Fluid Service. Most piping systems where ASME B31.3 is specified as the governing code are Normal Fluid Service. This article focuses on the required examinations for Normal Fluid Service piping that is welded. The other fluid service piping will have different examination and acceptance criteria. There are three examinations specified for the fabrication of welded pipe for Normal Fluid Service:
There are two items that are routinely misunderstood or not typically addressed by the contracting parties, i.e., owner and fabricator. The first is that the inspection of weld fit-ups and alignments before welding, and monitoring of welding in progress, is rarely performed by properly certified visual examiners. The second item is how to apply the “random” radiographic or ultrasonic examination requirements. Both issues are further discussed below.
Visual inspection of joint preparations and welding in progress assures that welding is being performed in accordance with the WPS’s by certified welders. It is required by the code to be performed by either a Certified Welding Inspector (CWI), or a Visual Level II inspector certified in accordance with ASME V Supplemental NDE Certification requirements which is based on SNT-TC-1A. It is an important step than can minimize weld rejects that occur due to the random radiography or ultrasonic examinations. Many welding contractors do not want to incur the additional cost of these inspections and owners don’t always have an understanding of the code requirements or enforce them on the contractors. Depending on the size and complexity of the project, the visual examinations before and after welding usually requires just one additional call out to achieve compliance. It is best performed on the first day of welding activities. Additionally, the examination of the welding certificates and records can be achieved during this inspection. Contractors should include these inspections in their estimates so that cost does not become a prohibiting factor for making the inspections.
Random radiographic or ultrasonic examination is required on not less than 5% of circumferential butt and miter groove welds. Often, the NDE laboratory is called to perform these examinations after all welding is completed. Upon arrival to the project, the NDE technicians are told to examine 5% of the welds at random. This does not usually result in conformance to the examination requirements of the B31.3 Code. The first issue is that the welds are supposed to be designated by “lot” and that the welds to be examined in each designated lot shall include the work product of each welder or welding operator whose welds are part of the lot. For this to happen, a list of welds showing weld number, pipe size and thickness, location, welder mark, WPS used, and date welded should be presented to the examiners. This information is important in not only establishing the lot but is also needed if there are any rejectable welds found so that additional welds made by the same welder can be examined as required.
The next question then is what constitutes a “lot”? B31.3 states: “The quantity or extent of a designated lot should be established by agreement between the contracting parties before the start of work. More than one kind of designated lot may be established for different kinds of piping work.” The B31.3 Code references Pipe Fabrication Institute Standard ES-48 for examples of lot selection. Lot selection can be a source of dispute and therefore it is strongly recommended that the quantity or extent of a designated lot should be established by agreement between the contracting parties (owner or owner’s representative and contractor). This is something that is rarely, if ever, addressed in the project specifications or on the drawings. Specifying lot designations in the plans and specifications should be the responsibility of the owner or owner’s engineer. In the absence of such designations by the owner, lot selection becomes the prerogative of the contractor. In this case lots can be designated however the contractor deems appropriate but should be in accordance with ES-48. There are several options for establishing lot size including:
Once a lot is established, the next step is to randomly select welds within the lot making sure that each welder is represented. This should be based on the QC tracking system established by the welding contractor which should clearly identify each lot as well as the number of welds from each welder within each lot. Requirements for selection of welds to be examined within each lot should be agreed upon between the contracting parties (purchaser and contractor). Where no agreement has been made it would be prudent to allow the NDE examiner or other third party to select welds to be examined, otherwise the contractor would be responsible for weld selection. For erected piping systems where spool pieces were welded in the shop or fabricated on the ground, welds should be selected that are easily accessible by the NDE examiners. Otherwise, welds that were made in difficult welding positions should be selected for examinations.
Process piping spool pieces for fuel piping system
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