Piping Fundamentals

The piping system includes pipe, fittings, valves, and speciality components. All piping systems are
engineered to transport fluid or gas safely and reliably from one piece of equipment to another. Piping can be divided as • Small bore lines • Large bore lines As a general practice, those pipelines with nominal diameters 2” (50mm) are characterised as a small bore and preceding that as a large bore. Pipe sizes are on the basis of Diameter and Thickness. In some places, pipe size is designated by two non-dimensional numbers: Nominal Pipe Size (NPS) and schedule (SCH). Some major relationships:

• Nominal pipe size (NPS) is to describe a pipe by name only. Nominal pipe size (NPS) is generally related to the inside diameter (ID) for sizes 1/8” to 12”. For pipe sizes of 14” and beyond, the NPS is equal to the outside diameter (OD) in inches. Outside diameter (OD) and inside diameter (ID), as their names imply, refer to the pipe by their actual outside and inside measurements. The Outside diameter (OD) is the same for a given size irrespective of pipe thickness.

• The schedule belongs to the pipe wall thickness. As the number increases, the wall thickness
increases and the inside diameter (ID) is reduced.

• Nominal Bore (NB) with schedule (wall thickness) is used in British standards classification.
The main purpose of piping design is to configure and lay equipment, piping and other accessories
meeting relevant standards and statutory regulations. The piping design and engineering involve the following six (6) steps:

Selection of pipe materials according to the characteristics of the fluid and operating conditions including maximum pressures and temperatures.

• Finding economical pipe diameter and wall thickness.

• Selection of joints, fittings and components such as flanges, branch connections, extruded tees, nozzle branches etc.

• Developing piping layout and isometrics.

• Performing stress analysis as per the potential upset conditions and an allowance for those upset
conditions in the design of piping systems.

• Estimating material take-off (MTO) leading to material requisition.

The Pipe Material Specification (PMS) is the major document for piping engineers. This document
describes the physical characteristics and specific material attributes of pipe, fittings and manual valves necessary for the needs of both design and procurement. These documents are contractual to the project and those contractors that work under them. A piping specification must contain those components and information that would typically be used from job to job. The following items below provide the primary component report and notes required for a typical piping system. − Pressure/Temperature limit of the Limiting factor for Pressure/Temperature − Pipe material − Fitting type, rating and material − The flange type, rating and material − Gasket type, rating and material − Bolt & nut type and material Manual valves grouped by type − Notes − Branch chart matrix with corrosion adjustment 1.14. DESIGN FACTORS The design factors that affect piping engineering include:

• Fluid Service Categories (Type)

• Flow rate

• Corrosion rate

• Operating Pressure and Temperature All this information is available in the Process Flow Diagrams (PFD’s), Piping and Instrumentation Drawings (P&ID’s) and Piping Material Specification (PMS).

What is Quantity Surveying?

 Quantity surveying refers to the cost management, procurement and contractual issues in the supply chain and marketplace. They usually advise on cost implications of the clients’ requirements and other stakeholders’ decisions. They monitor and update initial estimates and contractual obligations as the construction progress based on additional works and variations. The practices do provide services that are focused on buildings (the architectural elements), and civil engineering now provides services that include heavy engineering, oil and gas, and building engineering services. Although the engineering services are part of buildings, it would be out of place to claim that all quantity surveyors have the required skills and knowledge to provide expert advice on building engineering services as they do for other aspects of construction. Most of the quantity surveying practices consider building engineering services a specialised duty. Most of the building clients have become uncomfortable with the inability of quantity surveyors to provide conclusive and accurate estimates for their buildings arising from using lump sum approaches to price engineering services. Today, it is common to see or hear statements like ‘M&E Quantity Surveyors’ ostensibly to mean quantity surveyor that is ‘qualified’ to offer advice on building engineering service. Many of the universities now offer a degree in building services quantity surveying which aims at providing students with a sound understanding of the principles and practices involved in the building services quantity surveying specialism, up to degree level standard, and to help them in the progression to Masters the level should they so wish. A general question is if such degrees are required considering the knowledge and skills expected of quantity surveyors in the measurement of building works. Quantity surveyors have a background rich in the dynamics of costs of construction. Arguably, such degrees are not warranted. Several studies show that quantity surveyors have generally expanded on the nature and scope of services they now provide. In order to understand this, we evaluate the levels of involvement of quantity surveyors in the procurement of building services engineering. The study aims to provide fresh knowledge on the expertise of quantity surveyors with a focus on the procurement of building engineering services. This knowledge is valuable to academic institutions that offer quantity surveying programmes, practising quantity surveyors and other players in the construction industry. Quantity surveying is universal. However, it is carried out under different names. In a few countries, quantity surveying is very much related to cost engineering, while they are also referred to as cost economists or cost consultants in other places. However, quantity surveying is not just a simple thing. As such the phrase “quantity surveying” is a catch-up term that hides a multitude of meanings. The modern quantity surveyors perform various types of services that extend beyond the services traditional quantity surveyors provide and higher institutions offering quantity-surveying programs are responding accordingly by modifying and upgrading their course content. Quantity surveyors must provide advice on the strategic planning of a project. For the construction worker, this advice affects clients’ decisions on whether to construct or not and if the client decides to construct what effect does cost have on other criteria within the clients/users value systems including time and quality, function, satisfaction, comfort and aesthetics.

What is Submerged Arc Welding?

In Submerged Arc Welding (SAW) process, the arc and the molten weld metal are covered by an envelope of molten flux and a layer of unfused granular flux particles. The arc is literally submerged in flux, as such the process is relatively free of intense radiation of heat and light. In most typical open arc welding processes the resulting welds are very clean. Like Gas Metal Arc Welding (GMAW) process, SAW process makes use of a solid wire electrode that is consumed to produce filler metal. The arc currents are usually considered to be very high (500A to 2000A). The efficiency of transfer of energy from electrode source to the workpiece is very high (usually over 90%), since losses from radiation, convection and spatter are minimal. The deposition rate along with the weld reliability is good. A reduction in Cost and improved productivity in welding operations can, therefore, generate a considerable impact on the competitiveness of various manufacturing industries. At the time of welding, joint preparation and arc efficiency are the most important factors dominating the cost and productivity of the weld. The desired amount of weld penetration must be achieved in a single pass the welding speed will be the major factor that determines the welding time. The efficiency of the arc is determined by proper penetration as well as the productivity of quality welds. The filler material is an uncoated, continuous wire electrode, that is applied to the joint along with a flow of fine-grained flux, which is supplied from a flux hopper via a tube. The electrical resistance of the electrode should be as low as possible to facilitate welding at high current and so the welding current Is supplied to the electrode through contacts very close to the arc and immediately above it. The arc burns in a cavity, which it is filled with gas and metal vapour. The top of the cavity is formed by molten flux. The solidified weld and the solidified flux covers the weld in a thin layer and which must subsequently be removed. The excess flux can be reused again. It also has a thermal insulating effect that reduces heat losses from the arc. As a result, more of the input energy is there for the process of welding. There are greater thermal efficiency and a faster rate of welding. It has been found that there is greater thermal efficiency in submerged arc welding that shields metal arc. The thickness of the part is considered important in developing the desired penetration. The procedure for welding stainless does not show much difference in stool steel does not differ greatly from that of welding mild steel. The material being used is expensive and necessary conditions of service are usually required necessitating extra precautions and attention to detail. Stainless steel can be welded using either A C or DC with as short an Arc as possible in order to overcome any possibility of alloy loss across the arc. When using AC, slightly higher current and setting may be required. While welding in the flat position, stringer beads should be used and, if weaving is required, this should be limited to two times the electrode diameter. The heat input, which affects the corrosion resistance and leads to excessive distortion, should be limited by using the correct electrode diameter to give the required bead profile and properties at the maximum travel speed.