BSP Thread Archives - RYCO Hydraulics
The three types of hydraulic connectors and their two key functions

This article is an overview of the theory of hydraulic connectors, the three main types of connectors and the two key functions that all hydraulic connectors must fulfil. Three Main Types of Hydraulic Connectors It provides basic information about the three main classes of hydraulic connectors: Tapered Threads Metal seal connectors Soft seal connectors Two Key Functions of Hydraulic Connectors It’s important to understand that there are two functions that a hydraulic connector must fulfil: Holding Sealing Sometimes the holding and sealing functions are provided by the same mechanism, and sometimes by two different parts. Hose connectors may seem very confusing because of the many different types available. However, when looking objectively, connectors will always simply do two things. Hold, and seal under pressure. Development of Hydraulic Connectors Hydraulic connectors were developed in this order: Tapered threads Metal seal connectors Soft seal connectors Tapered Threads Tapered pipe threads were one of the first ways to connect pipes together. They involve cutting the pipe thread in a tapered manner, so that the diameter of the pipe changes over the length of ...

Tapered Pipe Threads – The earliest hydraulic connectors

Pipe threads were invented to join pipes together. Pipe threads are cut into a tapered form, which means that the diameter changes over its length. The taper is usually a gain of ¾” diameter or 12” of length (or 1 degree 47 minutes). Tapered threads were among the first methods of sealing a threaded connector. The threads pull and hold the parts together, and also provide the method of sealing. The thread is cut to a taper. In this way, the threads will “take up” the gap between the male and female components as they are screwed together. Sealing on a thread is an older method, and as a consequence, has become less preferred. Problems with Tapered Pipe Threads Some of the problems that pipe threads create are: Leaks The sealant may cause blockages Orientation is sometimes difficult Pipe threads cannot accept tube Let’s look at each of these points more closely. Leaks with Pipe Threads Once the threads are screwed together, the thread will bind and seal on the flanks. However, even though there is a close assembly of ...

Metal Seal Connectors – A better alternative to tapered threads

Machined faces were added to tapered pipe threads in an effort to address some of the shortcomings of pipe threads. A deep 30 degrees chamfer was added to the face of thread to form a seat. This is a modification that is only really seen in hydraulic products due to the high pressures involved. While a tapered pipe thread is still used, the thread no longer provides the sealing function. The thread now only provides the holding function, which is a fundamental change in its use. The machined face provides the following benefits: Easier orientation Better sealing No need for sealant The 30 degree machined face was first developed for the British pipe thread, BSP. That way the advantages of the sealing on the machine seat are available in the America thread also. Metal Seal Pipe Thread Types British Pipe Threads: British Standard Pipe Taper (BSPT) British Standard Pipe Parallel (BSPP) American Pipe Threads: National Pipe Taper (NPT) Advantages of Metal Seal Pipe Threads These connectors have a greatly reduced leakage when compared with simple pipe threads. Disadvantages of Metal ...

Soft Seal Connectors – The ultimate hydraulic connectors

Soft seal connectors are a modern development in hydraulic connectors, intended to address the most common issues with older designs, including leakage and the effects of vibration. They’re also designed to work in much higher pressure systems, to meet the growing needs of a wide range of applications across different industries. Soft Seal Connector Definitions Elastomer noun (Chemistry) An elastic substance occurring naturally, as a natural rubber, or produced synthetically, such as butyl rubber or neoprene. Elastomeric adjective (Chemistry) A part that has an elastic quality about it, or one that uses an elastomer. Soft seal, or elastomeric connectors use a soft seal to complete the joint, resulting in a leak free and vibration resistant joint. The seal is usually an O-ring. Advantages of soft seal connectors Soft seal connectors have a number of advantages, including: They are positive sealing Resistant to vibration Very high pressure capability Easy and quick to assemble, which is important in high-volume production Disadvantages of soft seal connectors The O-ring in soft seal connectors may harden with heat or soften with incompatible system fluids, so ...

Tapered pipe thread hydraulic connectors – BSPT and NPTF

Tapered pipe thread hydraulic connectors have an outside diameter that is cut on a cone. This results in sides that are not parallel. Two common types of tapered thread connectors are BSPT and NPTF. BSPT British Standard Pipe Taper Country of origin: Britain Thread angle: 55 degrees (Whitworth) Seat angle: 30 degrees BSPT is a tapered thread. This means that the outside diameter of the thread is cut on a cone. The sides are not parallel. The taper angle is a rise of 3/4" for every 12" in length. This is approximately 1 degree, 47 minutes. Male BSPT threads mate with female BSPT threads in adaptors. BSPT female threads are also used in port applications. As BSPT ports seal directly on the thread, the only machining required is drilling the hole and tapping the thread. BSPT threads can also be used as a machined seat connector. The thread used in the female swivel is parallel, BSPP. This is so that the connector bottoms out onto the sealing face. The female swivel is made as a two part assembly. The majority ...

Metal seal hydraulic connectors and their uses

Metal seal connectors use profiled metal surfaces on the connector to form a seal. There are many different types of metal seal connectors, including JIC, DIN, BSPP and JIS, NPSM, and they are used across many industries. JIC Joint Industries Council Country of origin: USA Thread angle: 60 degrees (UNC / I-INF) Seat angle: 37 degrees JIC threads are parallel. The thread used is a unified thread, either course; I-INC, or fine; UNF. JIC are the most popular hydraulic connector form due to their versatility. They can connect to both hose and tube. When connecting to inch tube, it needs to be flared and a tube nut and sleeve, (RYCO part number S6), are required. Metric - DIN 2353 Deutsche Industrie Normen Country of origin: Germany Thread angle: 60 degrees (DIN 3853) Seat angle: 24 degrees They have a 24 degrees internal machined seat. These threads are becoming much more common worldwide. Like the JIC connector, there are DIN threads that can connect to both hose and tube. Unlike all other thread types, there are three sub-groups within the DIN ...

Soft seal hydraulic connectors and their applications

Soft seal connectors use an elastomeric object to create a leak-free seal, they can take the form of bonded washers, encapsulated seals and o-rings. There is a wide range of soft seal connector types, including BSPP, DIN, ORFS and SAE. BSPP British Standard Pipe Parallel Country of origin: Britain Thread angle: 55 degrees (Whitworth) BSPP threads are also an elastomeric connector. A soft seal is used to ensure a leak free joint. RYCO use an O-ring and metal back-up ring or an encapsulated seal to complete the joint. In port applications, the seal is made by an elastomeric seal at the base of the thread, and not on the machined seat. BSPP port threads are very commonly used in Australia, but are becoming less preferred. BSPP threads can also be sealed by other methods such as an encapsulated seal or a bonded washer. When a bonded washer is used, the shoulder of the thread must be machined to a cone to keep the washer away from the edge of the thread. The photo below shows an encapsulated seal. This sealing ...