Copying nodes depending on children values

The input XML needs to be refined to contain only nodes where the value element of a characteristics element where the name attibute is weight is greater than 15.

XML

<root>
    <quality>
        <batch id="1">
            <characteristic name="weight">
                <value>12</value>
            </characteristic>
            <characteristic name="length">
                <value>45</value>
            </characteristic>
            <characteristic name="volume">
                <value>67</value>
            </characteristic>
        </batch>
        <batch id="2">
            <characteristic name="weight">
                <value>12</value>
            </characteristic>
            <characteristic name="weight">
                <value>17</value>
            </characteristic>
        </batch>
        <batch id="3">
            <characteristic name="weight">
                <value>56</value>
            </characteristic>            
            <characteristic name="volume">
                <value>65</value>
            </characteristic>
        </batch>
    </quality>
</root> 

XSL

<xsl:transform 
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
    version="1.0">
    <xsl:template match="/root">
        <quality>
            <xsl:copy-of select="
quality/batch[characteristic[@name= 'weight' and value &gt; 15]]
                                   "/>
        </quality>
    </xsl:template>    
</xsl:transform>